The Office was decent but it relied on that 'looking at the camera' thing, which was just a gimmick - and not a particularly innovative one, if you know Eric Morecambe. It also pushed the 'cringe' factor too far. Phoenix Nights had a far better range of characters, the actors really excelled and could add their own individuality to them, whereas in The Office they're all doing pretty much the same thing. Once you get past Gervais & Freeman the rest are just rotated around to make the joke, except Ralph Ineson who was fantastic as the salesman - and as someone who worked in that industry, I can say he was spot on.
There really is no comparison as to which is the best.