I think primary motivators should be, does the truck have the features you want, and is it in good condition? Beyond this, everything else is kind of secondary. It's true that later TBIs or Vortecs will have bugs better ironed out, but that doesn't mean earlier ones are necessarily bad. As a carburetor guy myself, I've found my '95 to be easy enough to work on, although it's also been extremely reliable, so I haven't had to do all that much with the engine. My reason for wanting pre-'96/OBDI was that emissions tests aren't required for them here in Illinois. If it wasn't for that, I might have held out for a Vortec.
My biggest regret, EVER, is when I buy something that's in worse shape or has more rust than I'm comfortable with, or doesn't have the difficult-to-add features I really wanted. I've held my nose and done this, and have always regretted it.