Speaking as an upright, and electric bass player, I think it depends on where and what you plan to play.
If you're wanting to play stand-up, I'd suggest a used 3/4 size plywood bass. If you want/need to amplify, there's several makers of bass pickups out there that work pretty well.
There aren't a lot of full size basses out there. They are very large, and unless you're taller than about five foot ten or so, they can be a sweat to play. Bass response is generally a little better, but I haven't found that it's worth the hassle.Not to mention transporting the behemoth.Most basses you see out there are actually 3/4 size basses.
Acoustic guitar basses are tres cool, and feel good to play, and are fairly easy to electrify if they're not already equipped. Up here in Canadaville and especially in the Far North where I am, you'd have to order one specially.They're also kind of pricey, at least up here.
Electric solid body basses are easy to play and setup, but you have to spend a few bucks to get one that sounds half decent, has a usable and stiff enough neck, and has good enough pickups that don't sound like slush.
It can be a good idea to have someone check out an instrument with you. if you're not familiar with that particular style, especially if it's an upright. You don't want to spend a lot of money on splinters held together with 5 minute epoxy, duct tape and/or rubber cement.
Bonne Chance, eh?