NORM - I'd stay away from the tiny off-brand MIG welders like GLEN says. Miller & Hobart are both owned by Illinois Tool Works and are very similar and either one is a very good welder. Not sure about the current Lincoln welders but years ago you used to have to use ONLY Lincoln consumable parts on the MIG torch, contact tips, gun liners, etc, and they were much more expensive than the industry standard Tweco MIG gun parts, and the whole wire feed mechanism was molded plastic which is why My MIG is a Miller. ESAB is a good welder I'm told but every manufacturing plant I've ever seen has used blue (Miller) welders where the ability to stay running depends on reliable welders. ESAB is imported from Europe, and their website looks like they catter more towards the larger industrial rated welders where Hobart, Miller, & Lincoln make many sizes of welders for the D-i-Y'er. Also, to weld aluminum with a Spool Gun attachment you will probably have to get a larger 220V welder because it takes extra circuit boards inside the welder to control the wire feed motor inside the spool gun. I'm not aware of any 110V MIG's that can weld aluminum unless you run the proper gas and install the spool of alum. welding wire in the welder. Miller makes the spool gun for welding aluminum because the soft alum. wire tends to make rats nests between the feed rollers and where the wire starts running thru the cable to the mig gun. The Spool gun has a very short distance to feed the wire, the small spool of alum. wire is mounted right on the MIG gun. No wire feeds thru the welding cable.
Normally I recommend a 220V MIG welder so you have the capability of welding thicker steel, say 1/4" to 3/8" in a single pass but since you have an arc welder already you have that covered, a mid to larger size 110V MIG would work good for what you want to do. And I'd get the gas regulators so you don't have to use flux-cored wire, it splatters just like arc so what's the point? Since your arc welder is a Lincoln you probably want to stay with a Lincoln MIG. I also recommend buying at your local welding supply shop, they are competitive and sometimes lower in price than a big box store plus they can assist you with service & repairs plus give advice on what wire & gas works best for what your doing. And if you get the gas kit you'll be there for gas refllls anyhow.
I'd also suggest getting copper backing pads for welding CC hoods, the weld metal won't stick to the copper and prevents you from blowing bigger holes in the hoods because the copper absorbs heat from the weld. Your welding shop should have them or Eastwood sells them. But any mostly copper flat piece works.
It's funny, but I bought 5 pounds of 1/16th inch 6013 weding rod years ago, and I successfully used it to repair some cracks in the cheap dump cart I have for use with my CC's, I couldn't weld the less than .040" thk steel as well with my MIG even set on the lowest settings. But my Miller-Matic 185, about a 12-13 yr old 220V machine is great on 1/8th inch steel and thicker. I bought a Miller Dynasty 200DX about 5-6 yrs ago to have aluminum welding capability and weld really thin material, but I'm not happy with my skills as a Weldor yet. I can't TIG two Coors Lite cans together yet.