Bruce,
That's a tough call because it will depend upon what you're doing and your skill level with the process. If you're going from mild steel to other alloys, a GMAW is real pain in the butt to change wire on all the time - that's why I have 5 wire feeders, three spool guns and three self-contained GMAW machines, each one set-up for a specific use and ready to go when I needed it but that was a major part of my business.
If this is something you want to park in the corner for an occasional small job, I'd have to say go with something like the Miller Maxstar or a similar high-quality CC (constant current for SMAW/GTAW) inverter power source. A good selection of electrodes can be kept on hand and changing from one alloy to another is simply a matter of putting a different electrode in the holder. If you see the reply I just posted under the other welding thread, at the bottom I explained about 1/16" diameter SMAW electrodes which are quite handy for the small stuff. The versatility of a SMAW power source and it's ease of use are the two biggest selling points. Also as I stated in the other post, you can do scratch-start GTAW with a good quality CC power source but it does take practice and if put it aside for a couple months, you've got to take the time to get the "feel" back again before you get into welding whatever it is you're needing to weld.
GMAW wire feeders definitely have their place but you'll see the comments in the other post about having to over-fill then do a lot of filing/grinding. With a SMAW and stick electrode, the angle at which you hold the filler rod in relation to the work as well as the current setting on the power source allow for much finer control of the weld. Say you're making a trigger guard, back-up the pieced to be welded with another piece of scrap steel, set the current for the stick to run smooth, start the rod on the scrap and when the arc smoothes out bring it into the weld, keep the rod at 90° to the work and it'll lay a nice flat bead on the work and as you come off the work, let it fill the end of the weld joint and break the arc in a sweeping motion off the scrap piece - just takes a little practice to learn how not to weld the work to the scrap. Same if you're going to fill a small hole or make a spot weld, lay a scrap piece next to the hole, start the arc on the scrap and come into the weld with a hot rod, let it cut, fill and break the arc by popping the rod strait up. If you want to build-up a surface, lower the rod angle to the work and lower the current, the lower the rod angle is to the work, the higher the weld bead will be.
The most common mistake made with SMAW welding is keeping the arc too-long. Keep the arc tight to the work - exception being when running high-cleaning electrodes like E6010 and E6011. For low hydrogen electrodes like E7018, you want the arc tight which lets you turn the current up without putting excessive heat into the work but still maintaining good penetration. By "tight" I mean you should be able to lay the rod against the work and feel the flux dragging on the work as you move the rod.
If you've never done any SMAW welding, get someone who knows what they're doing to teach you starting with vertical up then overhead - don't even consider putting a bead down in the flat position until you learn V-up & OH because learning in those positions will prevent you from learning all the bad habits that will make welding much more difficult to learn. You start long-arcing or laying the rod down in a V-up or OH weld and it'll all drop out in your face so you know exactly when you did the wrong thing. Having someone tell you what you did wrong is one thing, seeing it happen in real-time provides a much better understanding and much shorter learning curve. In addition to learning how to hold and move the rod correctly, you'll also learn how to set the current and control the heat input into the work all at the same time. When it comes to SMAW, FCAW & GMAW, I prefer running V-up over any other position whenever it's possible to do so.
