Hey, Ive had a couple of migs. First was a 120 amp single phase cig machine. Was OK but had some issues with wire feed when running ally.
Upgraded to a 420 amp Kempi with 4 roller feed and havent looked back. If you can run it go for 3 phase, much smoother and easier to get neat welds with.
4 roller feed makes life much easier with ally, I'd look hard for this feature. Also found "safra" brand ally wire to give very easy starts and less spatter than others I've used.