Depending on what you plan on welding you could go either way. TIG is probably better for detailed work but when you need to weld a lot in a hurry it is hard to beat a spool gun.
I was talking to a guy yesterday that puts non stick liners in aluminum belly dump trailers. Once they put the liners in they have to weld lips around the top to hold them in and keep the material being hauled from getting behind the liner. He said they run through 50+ spools of aluminum wire a day. Can you imagine how long that would take to TIG? On the flip side I have seen some people do very intricate work with TIG that would be virtually impossible with a spool gun.