Which Mig welder to buy?

220 amp welder hands down -better duty cycle , If you have 220 in shop get a 220 welder

115 amp welders are toys- short duty cycle and welding amps drop off very quickly

That's a little harsh, it all depends on what you need. For the casual welder who's only gonna use it 3-4 times a year, a 220 is way overkill...a decent quality 110 will be fine. Obviously, if you're a pro or will need to be welding truck frames or something heavy duty that's a different story.