Love this game:
Here's my current custom build:

1. Bone warrior (15)
2. Aberration (30)
3. Captain (110)
4. Roach (105)
5. Grizzly (180)
6. Dark templar (315?)

Captain and Roach and grizzly give good buffs, T1 can customize to 3, abbs take care of mech.
This is the set up I almost ALWAYS use.

Questions are- any replacements you'd suggest, and what are custom builds you use?