which support

If you like all in champions thresh, leona, braum are your choices braum and leona are very similer but I prefer leona. Thresh is a very dffiicult support and if you don't have the time then pick leona or braum because they are quite a bit easier. Leona can deal some major burst if her adc is with her at any stage of the game making her one of the strongest level 1 all in and her burst doesn't fall off untill pretty late in the game. Also, her burst comes from her passive which does magic damage so it cuts straight through most rune pages.

Nami has more of a passive lane prefering to stay back and not fight as much very different from the other 3 supports. But can all in very nicely as well but can't take too much damage when she does.

If you dou queue with you're adc or if you do teams of 5 then thresh is a very powerfull support better then anyone else imo. But he doesn't do extremely well with solo queue's random people unless in a pretty high elo. If you're willing to put time into thresh he can and will be the best support in most situations. If your planning on maining a support, thresh is a good for that too because he is pretty much immune to nerfs unless they completely rework his kit. He is immune to nerfs because all of his power comes from his very good kit and the only thing they can really do to nerf thresh is to raise your cooldowns and that still won't affect him too much.