Generally speaking, the smaller the hex size, the more critical it is to use a quality hex driver otherwise you run the risk of stripping the screw head. I am fussy with my drivers and have tried the following:
Wiha - the small, smooth handle makes it difficult to hold and generate torque. The tip is not bad but not great either.
Align - decent value for money but the tips are not as precise as I would like.
HK Turnigy - better than expected for this price point. Similar to Align in quality.
EDS - I have only used one of their power tool allen tips but was very pleased with their quality. Many RC car guys recommend these as the best value driver.
MIP Thorp - Very popular with heli crowd. Excellent handle and the tips are very precise. Disadvantages are that tips are not user replaceable and the handles are not clealy marked with the driver size. In metric, they are only available from 0.9mm to 3.0mm.
Hudy - Very popular with RC car crowd. These drivers scream quality. Tips are user replaceable. IMHO, they are just as good as MIP Thorp if not slightly better. Unfortunately, they are very pricey. In metric, they are available from 1.5mm upwards.
In summary, if you are on budget but still want quality tools, have a close look at the EDS drivers. If you want the highest quality tools, then both MIP Thorp and Hudy fit this bill. Hope this helps.