I have a Lincoln 135plus here at the house and have been able to do everything I've wanted. Even some 3/8 plate with passes on both sides. I use a 175plus at work (building nascar chassis) and even have used Bert Beagle's and will say If I had the service to do the 175 I would, but the 135 is slightly more handy. But, I have access to the 175 anytime I need it so take that into consideration. BTW the charts inside the door of the lincolns will get you close. And I would stay away from the newer 140s and 180s if you can. We've had alot of trouble with them and they seem really touchy to get right.
Also a good project is to build your own welder cart. Lets you be creative plus you can learn how to weld better while actually building something.
here's an idea:
