BF 1942 was probably the best overall in terms of balance and competative play, Berlin & Stalingrad were awesome maps, the reasons this was the best ? no stupid stats.. you joined a map and played to win and not fulfill some stupid requirement for a useless badge.
I enjoyed bf1942 more when Desert Combat mod came out.
A mod called Desert Conflict was released for BF2 a while back. It's a BF2 version of Desert Combat. It's been a slow developent but if you want an updated version of DC, you might want to take a look at this.
http://www.desert-conflict.org/