I would buy a high-end bow for one of the top manufacturers, honestly, I would avoid a used bowtech, they had a lot off issues there for several years with limbs.
A good used Hoyt Spyder, Nitrum, Alphamax would be a great bow that would last a really long time and could be picked up very cheap. I buy a lot of used bows for my wife and boys and have found 5yr old bows can be had for very reasonable prices.
I would also buy a fully set up bow, people don't want to mess around with pulling accessories and you can get them for not much more than a bare bow, just change the things you want to at that point. One thing about buying used is you really need to know your specs, exact draw length or range you need, draw weight, etc. if you don't know this stuff it could really cost you.
If you know your exact specs, prime makes great bows, they can be had for cheap used because the draw lengths are not adjustable so there isn't as many people looking to buy that exact setup as an adjustable bow.
If you don't know your specs either find them out or buy a bow with adjustable mods.
Some other really great bows are the Strothers bows, they were great reliable bows, Strothers went belly up so the bows are super cheap but very high quality. Moxie archery bought out there bows and currently make a lot of the parts that are exactly like the old Strothers stuff. I recently bought my oldest son a like-new Strothers bow for $150 to my house, there isn't a scratch on it and it was a $900 bow a few years ago.