[Truckstr]

dwaite said what I was going to say. You'd be smart to take a good hard look at what you need to do to your truck(s). Make a list of goals and the tools you'll need to do the various jobs. An air compressor was my first "big" equipment purchase and I used it all the time (and still use it and a newer, bigger one). But I had to buy a few other tools to go with it - air chisel, impact wrench, paint gun, air drill, sand blaster etc. If you buy an air compressor, make sure it's big enough to run all the air tools you'll end up buying.

Then I bought a welder. I use the air compressor a lot, but when I need the welder there's no substitute. A Sawzall is hard to do without. I bought a 7" sander/grinder too. The air comes in really handy. The welder is just as useful, but is for a completely different set of jobs. It all comes down to what you need to do. You'll have to figure that one out. There is no single "correct" approach. Some are just better than others.