Personally, I don't really care whether the program's proprietary or open source; as long as the program's fine with me using them the way I see fit. However, when I have to find an alternative, it just so happens that I look first in the open source ones, since they tend to be more accessible than the proprietary ones; though I don't mind sticking with what worked for as long as I could. BTW, for proprietary, the order of preference is freeware > premium non-subscription (that doesn't treat the users like crap) > everything else (subscription-only, premium w/Goolag dependency).
Some personal case studies :
First off, it began as a kneejerk reaction to Nova Launcher (an excellent but proprietary launcher app) being bought by an ad company. Searching for alternatives proved fruitless - Lawnchair & Neo Launcher is incomplete; OpenLauncher is abandoned, & other FOSS launchers has interfaces that don't mesh well with my personal usage (not to mention most other proprietary launchers tend to be Goolag Play exclusive, which is a massive no-no for me). In conclusion : I stuck with Nova Launcher (Prime) v7.0.57 without internet access; as it still worked for me.
With 3.20 (build 1164), AIMP completely fucked itself, ignoring the "jump to file beginning on single previous button click" option for headset commands by default, without any way to revert this behavior whatsoever; which unfortunately destroys any future prospects of AIMP for me (especially since future builds of AIMP doesn't revert this behavior at all). Simple Music (by SimpleMobileTools) came the closest to replacing AIMP, though missing one crucial feature : manual library scanning. Symphony is somewhat worse, suffering from being unable to properly input triple tap with media button to rewind / previous track (it gets treated as double-tap for next title & a single tap for pause instead; and headset button controls can't be tuned). Not to mention that most music players on Android (aside from AIMP, Simple Music, & Symphony) doesn't make life easy for those without playlist files. And so, I'm back to AIMP 3.10.1052.