First I need to clarify something that everyone seems to get confused... GMAW/MIG uses different kinds of wires, and all need to be used with an externally supplied inert shielding gas to make sound welds. Solid wire(Er70s-6,etc) are probably the most common and use argon/c02 gas mixes. Minor cleaning, easy to use and good quality welds. Flux core(FCAW) also needs a shielding gas, people use it without a shielding gas thinking the flux alone will protect the weld and when it fails they blame the process, however flux core used with a shielding gas has deeper penetration than solid wire and from my experience is easier to use out of position. Once you buy a wire feeder or MIG machine the main cost has already been spent, a spool of fluxcore or solid wire runs about the same price. Niether fluxcore or solid wire is better, used properly the both deposit sound welds. However, for hobby welding and minor repairs solid wire is the best choice, its quick, clean and user friendly. p.s. Just as an example, they build battleships with fluxcore and stick, not solid wire, when it comes to heavy steel fluxcore is what you want(just dont forget the shielding gas, wire is wire...they all need it)