I would say it would depend on your budget.. if your on a unlimited budget i would say get a few difrent machines for each process so you have leave them set up for a given task.. but if your budget its more limited i would spend the bulk of your money on the process you know you will do the most.. After that pick up what you can.. if you can only really aford 2 machines.. get something that can do aluminum tig.. and they get something that can do wire and stick welding. as both will come in handy from time to time..
i prsonly go heavier on Stick welding as alot of stuff i do i am forced to do outside.. and it also opens me upto welding more then one type of steel out side.. hence why my stick welder will blow the pants off my wire feed..
Biggest thing is spend the most money on the machine that is going to do what process you are planning to do the most.. weather it be TIG, MIG, Stick. and if your planning to do TIG aluminum make sure it has a few good AC tig functions and a GOOD duty cycle at the amperage your going to be welding in most often... its not a good idea to get a machine that you will always be maxing out..
RM Fab & Products
Miller 2E DC Welder Generator
Hobart "Auto Arc" 130
Klutch Plasma 275i Plasma Cutter
HFT 80 amp DC inveter stick
Hobard Oxy Torch using propane.
Metal Man FC125