I didn't say they were bad, but they're certainly not "better than everything else" like they once were. Heck, plain Tac squads are probably better most of the time now (though that changes a lot upon chapter tactics), or even better yet, crusader squads.
What IS best really depends upon what you want out of you troops. Cheap scoring? Mobile scoring? Something that's very durable? Someone that can actually fight? It's not as simple as it once was.
It's not that Grey Hunters are bad, it's just that calling them "best troop choice in the entire game" just reflects out of date thinking to an extent that it kinda blew my mind.
@Benjamin If you have a pure troop choice thing, it's unfotunately going to be all Imperial. Xenos troops mostly can't be tough AND do damage, and marine troops are really the only thing that can fill all roles. Plus, y'know, bike troops. I just don't think it would be very interesting.