For an atmosphere with Villa fans then Feed the Yak in Elephant and Castle is the normal meeting spot.
It's cute but isn't it a bit small now that the Villa boys "are taking ovah" and crawling out of the woodwork from Holborn to Holloway, Holloway to Heathrow ?
It's better than it used to be when it was just that shipping container. As I travel to most matches now it's rare that I find the reason to be there but I've heard the atmosphere is still good.
If less fussed about the atmosphere and want a plethora of screens then any of the '-Wood' bars tends to get my vote (greenwood, redwood etc). They're a bit sterile but if your focus is on watching sports and decent service over being in a good pub then they're great.