Principles are always better than friends.
If you share the same principles, it's cool.
If not, you make peace with that fact.
Don't do what they say if they disagree, and don't force them to do what you say if they disagree.
It's simple, and you'll probably still have friends if they are worth time. If not, and just not having the same system was enough to "ruin it", I'd suggest getting better friends.
Me and my friends main PC and make fun of consoles all the time.
We all recognize that the Xbone is a failure. One of our other friends likes it, but we don't belittle him for it nor do we try to actively change his mind. We still talk and are still friends, despite not sharing the same views. My hope is that eventually he'll see the light and be like "oh damn".
Amazing, eh?
But then again, I'm not one that is easily swayed by what others think. "Mob thinking".
I make my own damn decisions, and don't care too much if others make the wrong ones.
Just so long as my money isn't being wasted...