What you said is true... Different firms have very different cultures and that's what seperates the Big4. It's not to say which one is better than the other but Budgeted Revenue and Revenue per Partner are the only way to quantitatively compare them.
On a sidenote, whilst the pay may not differ that much in Big4 firms, did anyone see the article in BRW comparing Big4 and 2nd tier firms pay? It was quite interesting to see the differences "later on". Not to say the Big4 firm is better for the person, but it's just another quantitative measure we can use to compare and contrast. It's upto the individual to see which firm suits them best I suppose.
My friend is a very active, sporty, loud person and I thought he fitted into KPMG perfectly. I consider myself a bit more 'quiet' compared to him and I prefer to be a bit more 'reserved' and I think thats what made me more suited to PwC. Btw I apologise if I come off as being too pro my firm, but I guess when u think about it, we should all be grateful we have job security =]