World of Tanks

Tank destroyers. I've found that choosing TD trees at least allows you to do damage when you're outmatched. You might get destroyed in a few hits but you can hit back, even with stock guns. My heavy tank tree progression takes forever because you're saddled with shite guns until you get deep in upgrades.

I used to play a lot the past few years but I've gotten burnt out playing randoms and WarGaming killed Clan Wars/Strongholds so I don't bother with those that much either. Was in RELIC till it died then BULBA then back to RELIC after it was reformed.

Some general tips:

Keep an eye on your minimap as much as you can so you can know when you need to push/stay/leave/etc.

Use vision to your advantage as the random player in this game has no clue how the system works and you can easily manipulate in your favor

Look at the enemies team comp at the beginning of the game and then look at yours. If you're outnumbered greatly by heavies, probably a smart idea to avoid where heavies usually go (even in a heavy yourself because you'll just get swarmed) etc, etc.

Also I highly suggest watching streams/youtube vids of some of the better players in the game. I learned quite a bit myself from those.

If you have anything more specific such as tips in certain tanks, I'm more than happy to help.

I do recommend giving World of Warships a shot as well. Naval warfare is a nice change of pace.