Yep...I only use gasless when I absolutely have to do a remote job somewhere and gas would be a problem. Gasless is good for emergency repairs out in the field. It's also considerably more tolerant of rust, paint and contanmination. But does make kind of an ugly weld, yes, lots of splatter, difficult weld to clean and must be cleaned very very well if you don't want it to corrode even after painting.
Gasless makes nicer, better quality welds in most cases. You can also weld thinner sheet metal. Gasless wire (Flux core) only goes as small as .035"...which is too big for sheet metal like 22ga and below unless you are pretty good with it. But...with a small gas mig...you can still pretty much forget aluminum...they claim it can be done, but I've never seen a wire feed work on aluminum worth a shit without a spool gun. I've tried numerous times with both my wire feeders...I don't have a proper spool gun...the wire just ends up binding up in the cable and it's a mess.
You want a gas type mig cause they can be used either way...with gas and solid wire...or no gas and flux core. I'm sure all the brand names make a decent welder. Pretty sure Lincoln, Miller, ESAB and some of the others are still the original companies, made in the US. Some of the small Hobarts, and the Centurys etc are mass produced foriegn stuff. The older Hobarts were great, heavy duty machines.
It's worth the money to get a decent machine...just save up another couple of weeks and get something reputable.
As for oxy/act...if you know how to use it...it's the most versatile welding system you can use. And probably the best overall for race bike fabrication. It will literally weld anything if you know what you are doing...and you can cut, heat, bend, weld very thin metal, braze and solder. Takes skill and patience.
Lot of freakin typing for a blind man.