762, you're going to have to provide on-screen evidence to back up a claim like that.
I think the Saladin doesn't translate well to TMP because it can't get away with being that spare in a detail-laden era of Trek design. A TMP Saladin seems lacking... too simple. The TOS Saladin can get away with it probably because there isn't much going on in the TOS era of design anyway. Next to ships like the Exelsior and Miranda, a TMP Saladin seems under-equipped. On the other hand, the TOS Akula looks like a kitbashed version of the Saladin... a poor man's hot-rod at best. At worst, it's an attempt to disprove the Saladin by adding another nacelle to the design to make it "work".
I rationalize Federation Destroyers of The Original series thusly: TOS Saladins were refitted to Akula specifications. Just as the "Enterprise Class" takes the name after the first constitution refitted, the Akula was the first destroyer refitted to its specifications. Unlike the Constitution-Enterprise, a more radical approach to making the Saladins useful was needed. It was still cheaper than constructing whole new frames, and the destroyers were already useful and proven craft in the Federation. Upgrading took more than they expected. Or something.
It's hard to say what Fanon design is my favorite since I generally mix and match my own perspectives on what's cannon. I suppose the Akula itself is a very strong contender because it's so widespread in the TMP era publications. I'd say it arguably has the most attention of any non-cannon Federation Starship (making appearances in Klingon Academy, the Starfleet Command series, Shattered Universe, and having its own physical models crafted). The Akula is appealing because it is not a straight-up kitbash, but it fits very well alongside the likes of the Constitution and Miranda so much that you could believe ILM designed it for a movie. I can truly believe these are the workhorses of the Federation, and would fly them more if Destroyers weren't so underwhelming in SFC.
Of the other races, generally I like the Klingon Academy range since Starfleet Command has so much of an influence on my perceptions of trek-dom. However, I also like the look of the FASA fleet in regard to the Klingons, especially as replacements for the disappointing few in the KA Fleet (the Light cruiser, for example, looks like a toy in the KA range and I wish it could be replaced by something like the L-9 Saber). I don't like the SFB range because it's basically the D7 repeated with minor variations.
When it comes to Romulans, I think the Imperium (Firehawk) from KA is probably my favorite. I like Romulans derived from the Bird of Prey, not ships evolving towards the D'Derix. The Imperium evokes the wings of the Bird of Prey and maintains a strong bird motif without calling the vision of the TNG era. Plus, flaming birds is always a good thing. From the FASA Range I have a strange attachment to the V-30 Winged Defender, probably from how cool the painted mini looked in that one Trek magazine for Trek 5 I had as a kid.
A final note has to go to the Baton Rouge and Mann class Pre-TOS Federation craft. When other classes seem so much like kitbashes nowadays, these examples prove nice notes of variety in an otherwise samey design lineage.