I use MT3 collets, mine were a set from Chronos I think, tho might have been RDG. The main issue with them is that they are fine for fixed sizes of tooling, but don't clamp down like the ER collects so if your set has 6, 8, 10 you're a bit stuffed if you want to hold a 6.4mm or a 9.5mm drill bit for instance (now tell me you shouldn't use a collet for holding a drill bit!)