Many of you know I work at my LHS... I ALWAYS reccommend the Team Associated hex driver set:
http://www.hobbypeople.net/gallery/554568.asp
We use those in the store and I use them at home. So far I have yet to replace a tip, although my 5/64" (2mm) tip is wearing a bit... But that's also the driver I use the most (and have been for over a year).
Prior to this set I used Duratrax ones, and went through a new tip on each driver before getting the Associated set. However, I do occasionally use the Duratrax 2.5mm ball driver for tightening up hard-to-reach screws (3mm cap, 4mm countersunk, and 4mm button head screws).
Every wrench in the Associated set can be taken advantage of:
0.050" - set screws on MIP CVDs
1/16" - Robinson Racing pinion set screws, Losi/Associated screws
5/64" / 2mm - any metric RC
3/32" - Losi/Associated/XTM
1.5mm - any metric RC
2.5mm - any metric RC
3mm - 4mm cap screws, 5mm button head or countersunk screws on engine mounts