I think what you need is someone with a lot more
experience than I have, so hopefully they'll come along, but you can probably get more concentrated knowledge at e.g. Ravelry.
I own a pair of
Ashford hand carders. I bought them at a
local yarn shop because that's what the spinner who owned the shop used and sold. She had good reasons to recommend them over competition, but I got them like 12 years ago and don't remember the details. They seem to do the job, but I've never gotten good or fast with them, but they're fine for blending cute little rolags.
I also own a
Brother drum carder which I love to use, but I've never used another drum carder, so I can't give any reasons why it's better. I've had it for ten years and bought it because my research on Ravelry showed a bunch of satisfied customers and it wasn't too too expensive.
I have watched women process wool and mohair on big combs and their comfort with the biomechanical practice is kind of enchanting, but I've never used one myself.