There are a bunch of nice presses available on digitsmith now. If you have the room at least get a 6/4. This comes in handy even when not doing a 6 color job. Like your doing your 3 color job now. You can leave in on the press and do a few 1-2 color jobs so that until your satisfied that all 300 are good and a few days for you customer is happy or doesn't want 1or 2 more.
Workhorse is an ok press. If you have the silver press with micros the micros have about the same amout of slack. I know I have owned both these press.
Riley Hopkins is ok I personally don't like the joystick. Micros are better than workhorse.
Hopkins international ok press not sure on parts availability though
Lawson I had an older one and was ok held great registration I did like the side clamps.
Rototex. These things are tanks hold great registration. Even the really old ones.
M&R. This is my favorite press so far. I have the 6/6 sidewinder and a bbc 16x16 and 3 color all flash I can load print and send though conveyor anywhere from 80-160 shirts an hour depending on how hard I want to work maybe more.
I had a 6/2 after a 4/1 and it really didnt speed up printing that much. Plus there was a small registration variance on the silver press between stations and that is not adjustable on the silver press. I made my money back but the Lawson and M&R really shined for registration and speed. The Riley, Hopkins international, rototex , I only test drove and short print runs. The others I have owned. The m&R will be with me till I retire or quit screen printing even if I get an auto.