I understand the thinking on the 92, but the Bosch brake system's potential for failure is a big negative for me. The 93's have a lot more horsepower, more comfortable seats, totally different suspension, and standard Eldorado brake, suspension, and radio components.
I have owned a 91, 1 92, and a super low mileage 93 and the 93 was by far the best one I had. It's all subjective and opinion, but a low mileage 93 is the best bet and if you are thinking about potential to appreciate in value, the 93 has it.
That being said, the leading Allante experts, Tom, Dick, and Johnny all seem to favor the phase II cars (90.5, 91, and 92) for their personal rides, and they are the experts.
Right now, values are down, and there are a LOT of Allante's getting parted out which will make the survivors all worth a lot of money someday. After all, it's a Cadillac, it's got an Italian built body, it's a two seater, and a convertible.
Name ANY car that is a two seater convertible, especially built by a high end carmaker that isn't worth money...
Corvette's, early T-Birds, Nash Healy, Kaiser Darrin, stuff like that. Once shunned and low priced, now extremely valuable.
Allante's, long-term, are smart investments, in my opinion.