MIG vs TIG

Is there any reason to use MIG over TIG welding ? Outside of maybe a spot you can't reach so well?

MIG is really good for welding something to your chassis. Especially older ones. If I am unable to get the metal as clean as I would like, I use my mig. It is much more forgivable when welding to dirty steel. Also much easier to learn. I also use it if I need to modify or fab a quick tool and don't care so much how it looks, as long as it works.

It is done with a single hand which is useful if holding something to tack or one's body in position; it's much easier to learn; it can be faster; it can be a continuous process as one doesn't need to keep grabbing filler rods; it is excellent for tacking; it can be used to fill gaps in heavier gauge quite readily; some cored wire doesn't need gas which can be useful if it's windy; between gas selection, filler wire and core flux options there is a lot of flexibility.

One big disadvantage is that it always deposits material - for some welds, especially thinner wall/gauge, this can be a problem.