If anyone still plays the single player mission, Surprise Reversed 2, having an assembled fleet (7 ships!) of TOS Romulans or Klingons is an impressive sight! The mission includes either a BB or DN, a BC, a CA, a couple of CL's, and a couple of FF's for the invader (three ships, CA, DD to DWC, CL) to shoot. Woe onto you if a couple of the big boys wake up unexpectedly! Given the TOS models we can all get, I think the Klingon and Romulan fleets look most impressive (and Anduril's rework is going to make it that much better)... I love Starfleet, but I'm just so used to looking at them that despite the truly beautiful and meticulous Federation models everyone has turned out, these other two empires' ships are really eye-pleasing. Gorn is almost there, but there isn't enough variety; and this is just way too true for the Hydrans and Lyrans.
After having said that and declaring once again that I'm an incorrigible TOS fan, the TMP Klingons REALLY look good... or was that TNG? Ah, TOS!