You'd be wrong then because MIG is as good a process as any of the others. It's the easiest to do but it does have a downside and you found out what that is. One can make welds that look great but in reality they are nothing but glued together metal. If I recall they call them cold welds. Penetration is vital to a proper weld. A MIG welder will do whatever you want just about but you have to set the machine properly or your welds are no good. The guidelines on the machines are a good starting place but every welder that I know of that uses MIG always does some test welds on metal like he's going to weld. Once you test your machine settings on similar metal of the same gauge as your project you will be fine. Someone once said that a chimp could MIG weld. But the caveat was that a human had to set the machine up for it first. MIG is all about getting the right settings on your welder. Once you have them right the welding is a breeze.
Hawke