I had a terrible experience with stick welding when I was in college. I got my first GMAW rig when I was restoring an old Willys Jeep about 30 years age and having to repair a lot of rust on the body. It was a Marquet 90 or something. It is a miricle I could weld at all with it because it wouldn't feed wire steady.
About 10 years later, I got a Lincoln 175 MIG and was pretty impressed with how clean the welds looked — and how easy it is. I've heard that you shouldn't MIG a trailer, but I know the first utility trailer I got was welded with a MIG because there were wires sticking out of the some of the welds. Miserable craftsmanship, they didn't even de-burr the cuts.
I've built a 4x8 light weight utility trailer to pull with my Honda CRV and a boat trailer for my Bass Tracker. Neither of those have fallen apart, so I must have done something right. I was welding 16 ga C purlin on the boat trailer and 1/8 angle on the utility trailer. I had a friend who is a genuine welder to weld the suspension parts for both of them. I made the suspension parts for the boat trailer with 3/16 angle and it bolts to the C-channel frame. It can be moved to dial in the center of balance and spreads the stress on the C-channel.
I make a lot of things for my clients with aluminum, so I want to be able to stick some things together instead of having to drill, tap and screw everything.
I purchased a rather expensive Lincoln 250 GTAW rig about 9 years ago and failed miserably with it, gave up and sold it. Last summer, I traded the Lincoln 175 for the Hobart Handler 190 with the spool gun (none was available for my Lincoln 175). Disappointed in my success with aluminum with the spool gun, I got a Hobart EZ TIG. It was malfunctioning (it wouldn't auto start), although I was able to weld with it by touch starting. Encouraged by success, I returned it and upgraded to the Miller Syncrowave 210 and I love it. It is simple, fairly automatic and makes pretty good welds. It can be upgraded with a chip to allow higher frequency and pulse.
So, to answer your question (if you are still reading after all that), I had the MIG first. I've tried flux core welding but I prefer gas shielding because it looks better and is cleaner. I don't much like spatter. I absolutely love my Miller TIG welder. If I had to give up one (and I've considered it) I'd sell the MIG and do everything with the TIG, but there is almost no re-sale value for a Hobart Handler 190. It is a year old, I gave about $850 for and I've seen a couple on Craig's List last for several weeks at $400. I rarely weld anything thicker than 3/16.