Best extruders for 3D printing?

I realized that I have the positioning part of a 3D printer just sitting in a corner. It's a Wells-Index CNC mill that I hardly use anymore. Why not put an extruder head and a platen on it? So I have been looking at stuff online and there are many choices. So, for those of you out there doing this which extruders would you use? And which platen for that matter. I'm not sure how the extruder would be controlled with my control. I do have a 4th axis servo amp that is currently used to drive my home made 4th axis, but it could be used to drive a servo that feeds the extruder. The amp can be adjusted for even a small servo. On the other hand, I could use different software made for steppers and use the Gecko-Drive servo amps I have in a box to power the machine servos. Any advice appreciated. Thanks, Eric