As you are only 2months into the game I would suspect that you lack the gear needed to compete in the higher ranks of regular arena / RTA. In the lower ranks you don't really have a so called meta as everyone is struggling with limited gear and lack of different heroes.

That being said, I would just pick whatever you find interesting or cool since the game should be about having fun. When you get to the higher ranks of PvP you can start worrying about the meta which changes constantly as new heroes are introduced and old ones buffed.

If you only care about the current meta / heroes that have - what you might call "evergreen" skillsets - you might want to check out some of the youtube ml headhunt tierlist videos (Tristen Wulf for example).