Yeah, just make sure that whatever you decide to go for ultimately 'feels right' when playing. In some games a cover system in 3rd person worked horrible, felt completely influent, just totally not smooth enough to feel good when playing. In other games it worked relatively flawless, but felt a bit like cheating. Meaning, there's a bunch of things that need to be made according to what main perspective you decide to go for.

In fps games you usually don't really need a cover system so much, but leaning left and right might be a good idea to implement.

All in all if you spend lots of time to make beautiful main characters, you might as well make it a 3rd person game. In RPGs it works great too as you can see what items or weapons you carry around or what cloths you've bought/found. It has an added value to see things in 3rd person.

So I would first brain storm on what kind of game you're making, then go for what fits best. I'm sorry I haven't read the whole thread, no time,
Cheers