On a delta I think it is worth using 0.9deg/step motors instead of 1.8deg/step. They don't cost much more, but they improve the positioning accuracy, in particular along the Z axis. I recently received my 0.9deg/step motors and will soon be upgrading my Kossel with them. I can't advise you on brands, I have only used Chinese ones.
If you are into upgrades, I recommend Duet electronics. You get a great web interface, digital control of motor currents, and 30-second delta auto-calibration. If you don't already have FSRs or another good Z probe solution, you may also be interested in my differential IR height sensor. See [miscsolutions.wordpress.com] for details of my build.
If you are into upgrades, I recommend Duet electronics. You get a great web interface, digital control of motor currents, and 30-second delta auto-calibration. If you don't already have FSRs or another good Z probe solution, you may also be interested in my differential IR height sensor. See [miscsolutions.wordpress.com] for details of my build.