This is a kinda nutshelled list of custom ROMs I have used & experienced - and is available in XDA. SearX the internet and/or XDA for more details.
This list isn't valid if you build your own ROM, though.
Here are my must-have criterias:
As I play Fate/Grand Order, I want USB debugging to not self-enable on every boot, solely because it's a bother to get to settings & disable USB debugging on each reboots, and Fate/Grand Order will not run if USB debugging is enabled.
Again, Fate/Grand Order requires Play Services. However, Goolag telemetry is badciv IMO. Not a requirement if GApps is used.
As stated above, Goolag telemetry is badciv. Though, for those who need GApps, BitGApps should fulfill those needs. OpenGApps of all variants have SetupWizard, and may sometimes force the user to connect to the internet.
Because it's the most recent stable Android version for now?
05/09/2019 Edit : Android 10 dropped - but I'll wait & see, as FGO hasn't supported Android 10 and there's no ROMs based on Android 10....yet.
17/09/2019 Edit : Custom ROMs based on Android 10 is available - but still, mostly Alpha / Beta, so bugs inbound, and there's the question about signature spoofing support.
29/10/2019 Update: With the rise of Android 10, devs may discontinue Pie builds in favor of A10 builds. Building your own Pie ROM & backporting security patches are recommended, though personally I have no knowledge of how to do so.
and some nice-to-have ones:
Saves me the hassle of having to charge to 80% & keep it plugged in as I get it to encrypt.
CAF is simply better when it comes to performance - though it's behind AOSP in security patches.
Just for the looks, and rice.
For the record, the ROMs are tested with a 6/128 Pocophone F1 (A-only), 4/64 Mi A1 (A/B), and 4/128 Pixel XL (A/B) Sure, there are Treble ROMs, but I haven't tried them yet.
17/09/2019 Update : Recently obtained a 4/128 US998 LG V30+ (A-only, just like the F1). What's interesting is that despite being an A-only, USB debugging self-enables (if enabled by default) only on 1st boot.
24/09/2019 Update : Flashed 20190913 AOSiP build for F1 (which apparently has inbuilt vendor), and discovered that USB debugging self-enables only on 1st boot. Not sure about other vendored builds for F1 though - didn't even bother testing them for now... Also, dropped the Pixel XL due to a severe lack of custom ROMs.
With my criterias out of the way, here's the list:
The most customizable AOSP-based ROM in my opinion. Supports signature spoofing (requires a toggle in Settings > Havoc Settings > System), although it isn't preloaded with microG / F-Droid. On my F1, the available RAM goes down all the way to 2800MB (which is far less when compared to most custom ROMs' 3400MB standard), which raises some questions. On the bright side, USB debugging doesn't self-enable on boot & GApps is not included.
As of latest build, HavocOS devs abandoned Pie builds in favor of Q. Gotta make a rant soon.
Availability: Poco F1(vendored build self-enable ADB on 1st boot only), LG V30(Unofficial), Mi A1(no GApps, USB debugging not self-enabled, sigspoofing support toggle in Settings > Havoc Settings > System)
Literally AOSP with VERY little added customizations - including telemetry (with opt-out option). Unlike ALL other custom ROMs, you can't really restrict Wi-Fi & mobile data access for apps, unless you use AFWall+ (even then, you don't get to really control network data access for some apps that actually don't need it). Supports signature spoofing, no preloaded GApps and doesn't self-enable USB debugging on boot.
22/08 Edit : Just realized that they also had a font generator. It works - though it only supports 1 font at a time. If a ROM features the DU Font Engine; it may work.
2/11/2019 Update : While weekly Pie builds are available, keep in mind that the security patch is still on August patch.
Availability: Poco F1(no GApps, USB debugging not self-enabled, sigspoofing support, no inbuilt vendor)
Similar to CarbonROM, but with tidied up settings & added Wi-fi & mobile data restriction ability. Only thing I consider flaws are the lack of CarbonROM custom fonts, elves, green-clothed archers & SAO font.
22/08 Edit : Starting the August build, USB debugging is self-enabled by default. May have something to do with the new inbuilt vendor.
25/09/2019 Update : USB debugging only on 1st boot, just like vendored AOSiP. No forceencrypt on 1st boot.
2/1/2020 Update: Android Pie builds are abandoned by the devs for Q builds.
Availability: Poco F1(Discontinued)(no GApps, USB debugging not self-enabled [self-enable only on 1st boot with inbuilt vendor], sigspoofing support)
AOSP-based custom ROM with the most badass boot-animation (but no custom font engine to up the badassery). Supports signature spoofing (microG), but self-enables USB debugging on boot. Also, vendored builds come with forceencrypt.
24/09/2019 Edit : Recently tried the 20190913 build for F1 - and discovered that USB debugging self-enables only on 1st boot.
Availability: Poco F1(no GApps, USB debugging self-enable (as of vendored build, 1st boot only - tested with 20190913 build), sigspoofing support); Mi A1(no GApps, USB debugging 1st boot self-enable, sigspoofing support)
AOSiP-based custom ROM, with added custom font engine in exchange for a far less awesome boot-animation. Unlike the OG AOSiP, does not self-enable USB debugging on boot. However, may come with preloaded GApps on some of its supported devices.
Availability: Poco F1(Discontinued)(no GApps, USB debugging not self-enabled, sigspoofing support)
The most popular AOSP-based custom ROM available. Doesn't support signature spoofing, but its Trust security feature is a neat addition not found in any other custom ROMs. Also has its own telemetry, though you can simply opt out on setup.
Availability: Poco F1, LG V30 (Unofficial) (All untested, no GApps & no sigspoofing support)
Pixel XL, Mi A1 (no GApps, USB debugging not self-enabled, no sigspoofing support)
LineageOS with microG & F-Droid built in. Signature spoofing is supported, but done in a way that microG is the only one using it. On the F1(vendored), A1 & PixelXL, does not self-enable USB debugging.
Warning : for any reason, do not delete inbuilt microG & reinstall it as user-app. Currently, there's no way to grant sigspoofing permission to user-installed microG (user-updated should be fine).
02/11/2019 Update: Recently flashed LineageOS microG for F1 (2019/10/28 build), and, microG can't be used as location provider, even if location access is granted. Also, for the F1, inbuilt vendor has force-encrypt enabled by default.
Availability: Poco F1, Pixel XL, Mi A1(microG "GApps", USB debugging not self-enabled, sigspoofing support microG only) (F1 force-encrypt on 1st boot)
LineageOS with added aesthetic modifications. Self-enables USB debugging on boot & has no signature spoofing. At least you may opt out of its own telemetry though.
Availability: Poco F1(Discontinued)(no GApps, USB debugging self-enable, no sigspoofing support)
CAF-based ROM, though, quite similar to AOSP in terms of looks. Previously, supported signature spoofing (microG) & self-enables USB debugging on boot. However, includes GApps in all builds.
Availability: Poco F1(OpenGApps (no GApps on June & July builds), USB debugging self-enable (unsure about August build & further), no sigspoofing support except for June & July build), Mi A1 (OpenGApps, USB debugging 1st boot self-enable, no sigspoofing support)
Another CAF-based ROM like RevengeOS - though, unlike Revenge, does not bundle GApps. Self-enables USB debugging (1st boot only for vendored build), and has sigspoofing support.
Availability: Poco F1(no news, probably discontinued - though GitHub development is active) (no GApps, USB debugging self-enable [1st boot only for vendored], sigspoofing support)
AOSP-based ROM with some HavocOS vibes. Supports signature spoofing (with toggle in Settings > Liquid Lounge > Miscellaneous), and self-enables USB debugging. While the OG Pixel XL's build has no inbuilt GApps, some others may include it. Also, questionable active development also means that security patches may come late.
Availability: Pixel XL(Pie build discontinued per August build), LG V30(no GApps, USB debugging 1st boot self-enable, sigspoofing support toggle in Settings > Liquid Lounge > Miscellaneous)
Pixel-based ROM with added features. As it's Pixel-based, comes with GApps & has no signature spoofing support.
Availability: Pixel XL(Pixel GApps, USB debugging 1st boot self-enable, no sigspoofing support); Poco F1(Pixel GApps, USB debugging self-enable(probably, untested), no sigspoofing support), Mi A1(Untested)
The only custom ROM without XDA support. Based on LineageOS microG, with more inbuilt apps, /e/cosystem, and iPhone-ish launcher.
Availability: Pixel XL(microG "GApps", USB debugging not self-enabled, sigspoofing support microG only)