From what I've seen, the preferred choices would be Hayward / Goldline Aquarite or AutoPilot. In getting the links, I just noticed that AutoPilot has an above-ground unit. Sean Assam, an AutoPilot service manager, is a regular here, so he may have more info on those. My own experience is with Pentair Intellichlor units, which are not thought of as well. (And Pentair doesn't think of them as well, either: they've been shortening the warranty on them!)

I just noticed that both AutoPilot & Hayward have above-ground units. They look like they're pretty new . . . which is always a reason for caution. But the AutoPilot unit is rated to operate at 1,000 ppm of salt, which is not a problem for AG pools -- you'll go above that in a summer's chlorine use. Here's the brochure. Personally, I wouldn't recommend that unit (or any unit!) if it's new this year.

The Hayward / Goldline unit is available from Amazon; there are several models, and I don't know what the differences are; they all seem to be about $475. Here's the "Goldline AQ-TROL-RJ AquaTrol Above-Ground Pool Return Jet Chlorinator", and the brochure for that unit.

But, several people here know more about the individual models, than I do.