Where people run into friction with any of these, it could be price, it could be depth, it could be audio quality, so the price on its own is a poor way to pick between them. Every number here came off the product's own site, its US App Store listing, or both. Prices move, so check before you pay.
A few of these cost nothing, ever, not even after a trial period. WordSuccess, from Advanced Bionics, and ReDi, from MED-EL, are free word and sentence practice apps, and both work with any brand of cochlear implant and any brand of hearing device. Cochlear CoPilot is free too, but only if you have a Cochlear-brand cochlear implant and an iPhone.
Angel Sound is on the list because it costs nothing and it has been around a long time. Be honest with yourself about the design, though. It is dated enough that plenty of people bounce off it before they get anything out of it.