Hey, if you buy a game you like and want to play it, then play it. I have games I still haven't played but I will not miss out on new games because I have to religiously finish what I already have first.
Life happens, whatever your reasons for having one, do not be ashamed of your backlog. Do not play games to clear your backlog. Play games to enjoy the experiences they have to offer.
I would look at your backlog, OP and identify which one game from it you want to play. Go with your gut. Don't think logically, "it has to be a shooter because I am about to finish a JRPG..." Just pick a game. Pop it in. Forget about the others for now and just play it. Even if you are juggling platforms, at any given time, you are mostly likely playing only one single game. One game. That's all this journey is about.
Because we pay money for these things, I do certainly hope that at some point, your interest in those games will return. Otherwise, give them away if you can. There must have been a reason you committed your hard earned cash to each one of them. Why them and not another game at the time?
As a caveat, as OP has mentioned, tastes change. That's why it's important let the now now determine what you want to play. Today you will feel like a Civ buff but in 8 months if it remains untouched, you might be into visual novels.
You have a responsibility towards yourself to balance your purchase-consumption ratio.
LASTLY - do not let the current trends determine what you like. There is no shame in buying old DS games today in 2019 because that's what you're into.
I am all over the place. Sorry.
TL;DR: what's the one game in your backlog you have interest in? Play that. Don't even think about it too hard.
