2 is a far better produced season and one that has a much more enjoyable narrative with plenty more drama and better gameplay too, but I'd honestly say watch season one first.
It has an amazing cast, hilarious moments and it's enjoyable to watch the show find its feet, adapt and position itself as some BBUS/BBUK hybrid. It's the first US format season I watched and now the rest is history so hopefully it should do the same conversion to you
I also for the most part prefer watching things in order but that's just me
Watch 1, then 2. And then start on BBUS, 11 or 6 are good ones to start with if you like drama and divides. BB15 despite the bigotry is good and if you want recency it's the best option, this season has been good but it's not BBUS in it's traditional format so don't start with that.
All Stars is amazing and to me is as near perfection an AS season and cast you can get. That and BB2 are my favourite seasons but you're a way off that yet. Try BBCan to ease you in, watch BB6 or BB11 if you're committed, maybe BB15 after that, and then if you become a superfan watch from BB2 onwards
