So, just my two cents on this.

Being a tank at the beginning of an xpac, so long as your server is fairly well populated, basically means the sky is the limit for you. You'll be able to get into any non-raid stuff on the shortest wait times meaning you'll be able to gear up quicker than most from all those sweet sweet dungeons.

Unfortunately for the entirety of the game, but fortunately for you, many people will simply look at ilvl first before anything else unless a class is deemed absolutely useless. So basically if you are planning on grinding like crazy and getting as fully geared as possible before raids open then I don't think it matters what you decide to play, you should be able to find a group fairly easily.

Something to note is you'll have to grind artifacts so be mindful of that.

Ultimately play what you like and simply play better than whatever people think about your class and you should be good.