What is the best for playing ToPK?

I've just recently started playing in B/P groups with my ranger in the ToPK area and although the B/P groups seems to be somewhat standard everyone carries different variations of skills. I was in a totally awesome group the other day and it was 5 rangers, 1 MM, 1 Order and 1 Ritualist. Every other group I've been in never quite made it all the way through and they all used a monk instead of a ritualist (I guess 1 other team almost made it but 2 players dropped out near the end). So is a ritualist that much better in ToPK than a monk or was it just that I was in a very good group overall?

I'd say that your other groups weren't good overall. I rarley find it a problem, even if a ranger or two drops out early. If some of the other drop out however, it gets worse, but not impossible.