E9 (’89-’94) This is the one you want to get rid of
F5 (’95) One year only, better flow/higher pressure than E9
F8 (’98 E4OD) This is supposed to be the best one
This is a pretty good article that points out all the upgrades in good detail. There's a lot of folks who like the "Monster in a Box" version, but I have to say: if you know what you are looking for and you can live with installing well inspected used parts where acceptable, I think you can piece one together for less if you are patient and don't count the time searching. I had an excellent trans builder when I lived in Vancouver, and I was really surprised how confident he was in a good used pump. I was skeptical, but he sent me to Portland to a big trans parts warehouse to pick up a good used pump for my C4 transmission in my Pinto. I couldn't believe I was going to put a pump in that was less than $25 in a ten second car with a pretty loose converter, but he insisted and told me not to give it a second thought as my pump was functioning but showed some visible wear. After he installed the pump, the pressure increased measurably by about 40 psi, and my car picked up almost a tenth, and the trans never missed a beat.
https://www.fourwheeler.com/how-to/...rhaul-for-heavy-duty-towing-and-off-road-use/
