If your welding is limited to a very occasional bit of fixing this or that, a less expensive 110 welder will work. If you plan to really use it regularly, find a way to wire 220 into your garage.
I have made very fine field repairs with a simple Redi-Welder, the problem with which is that you have no control over anything but line feed speed. Making good welds with something this primitive takes practice and finesse. Flux core AC welders have more control, but are still flux core welders. Best used on heavier metal because flux core tends to burn in more than gas/wire feed systems.
By comparison, anyone can learn to weld with a good gas MIG welder in 5 minutes, and in a day or two will be welding like a pro. I prefer the units with infinitely variable output rather than the ones with only a few amperage settings because I do a fair amount of sheet metal welding. I also prefer 220V units to the 110V simply because of quality of construction.
The thickness of metal a welder will weld is usually stated in single pass thickness. By using overlapping multiple passes, you can weld almost any thickness of metal, but as the metal gets thicker, there is more thermal mass to deal with and the welder needs to run hotter to get a good bead down, so there is a practical limit, it just isn't the one published by the maker.
Also, the lighter units, and especially the 110V ones, have a limited duty cycle, and I would not be surprised to find that they, too, will require a bit of wiring in the garage, as most require a 20A circuit and most household circuitry is based in 15A breakers and 14ga wire. Even my plasma torch will pop a 20A circuit from time to time depending on the thickness of metal I am working on. Might as well wire for 220V. If you have a water heater or clothes dryer in your garage, you already have 220, you just need to extend the line and install an extra box.
