I don't put much credibility on polls and general consensus because it's not a accurate gauge. There is favoritism, there is not much thought put into a pick, there is people just riding the wave of mass perception and there is people who just have no clue about the topic.
No one is re-writing history. We are just looking at the competition they fought and assessing who's was better. I watched back then and well before that and I can tell you that not many were debating who's competition was better. The talks of who's division was better started beyond the 2010s once both guys cemented their legacies. I recall that Anderson had the edge early in the goat talks, but that was for a couple reasons. One, he was pretty dominant over his competition and two, GSP had a couple tougher performances vs Penn and the loss to Serra. So GSP's early title run didn't get off to the start that Andersons did. By the time GSP won his belt and defended the first time Aug of 08 , Anderson already was going into his 5th defense. But even with that said, not many were talking competition but rather just performance. Again, the comparison just wasn't there cause GSP was a bit behind. He caught up nicely post 2010 when he faced the best WWs. Both Andy and GSP had meh competition from 08 to 10.
But like I said. IMO, both guys had an equal level of comp when considering their title defense or title reigns. Whenever I see this topic everyone lists all their wins and compares Leitas to Hardy. Let's be honest, Lutter, Cote, Leitas and Serra, Hardy and Diaz are not even worth comparing here. They were filler defenses during their divisions being revamped.
It really comes down to their 7-8 best wins. Andy had Rich 2x, Sonnen 2x, Hendo, Vitor, Nate and Okami. GSP had Hughes 2x, Condit, Shields, Hendricks, Fitch, Alves and Penn. If you really compare these guys, it's pretty balanced. Both beat the divisional goats at the time in Hughes and Franklin. Hughes being the greater fighter IMO. Both beat an all time great in Hendo and Penn, but I think we'll agree that Hendo is higher on the list and certainly a more valuable win in the respective weight class. And you're left with 5 other guys that pretty much balance out.
You wanna favor one over the other slightly, I don't mind. But to say way better? Give me a break.