Acetylene is evil stuff. Anything over a few PSI and it becomes spontaneously combustive. Acetylene bottles are full of some stuff (I can't remember what it is...) which the acetylene is dissolved/contained in, to stabilise it. Even so... if you knock a full bottle of acetylene over... be prepared to RLF (run like feck), as there's an excellent chance it'll set itself alight in the bottle. Whenever there's a fire in a welding supply warehouse (you'd be surprised how often...) they close roads for 1/2 mile (~1km) around for a couple of days, because of the danger of the bottles going up. Nasty, nasty stuff.... but REALLY good for gas welding
Back to the topic at hand.... I've got both a MIG and TIG welder. The main advantage of TIG over MIG, is it's relatively easy to weld different metals (in particular, aluminium); and you can braze with it too. Most TIG welders will also do stick (arc) welding, so a ready supply of pure argon isn't totally necessary to use them. Yes, you can weld Al with MIG, but I'm told it's quite hard to do well, and of course you need the proper wire.
This Old Tony (search for him on YouTube) has done some nice videos about the merits of TIG welding; there's also some reviews by a chap called Doubleboost which are packed with information too. BTW, if you do get into ToT's videos, be prepared to lose a few days... he's really good at them.
I've never TIGged with a foot pedal - my old Murex beast (Tradestig 180 AC/DC) has a crank handle on the front of it to change the amperage... I can't even remember if I can adjust the clean vs. weld part of the AC cycle. But if you get it on song, it can turn out some lovely welds, even in my deeply amateur hands. I did, for a couple of years, try to use a Chinese AC/DC TIG, but never had much luck with it. I suspect it was faulty... you'd get a few inches of decent weld, then bugger all else except pops and farts.
MIG is much easier: Get something which will take gasless wire, but can also cope with gas if you want. Welding with gas is IMHO cleaner (no slag to clean up if you need to run over a weld for a second time), but probably not worth the extra hassle if you're not doing a lot of welding. Again, I have an ancient and enormous Murex machine with a crank on the front to set the power level (a Tradesmig, funnily enough!), but it's like spreading butter welding with it. Only a bit hotter, and less edible...