To properly respond I'd need that link that was posted either here or maybe Monte's board which has graphic pics of dozens of the various genre ships, from Star Wars, to Trek, to Robotech, to B5.
I am not sure, but you might have meant this:
http://www.merzo.net/
1.)
I really love the Babylon 5 Earth Cruisers. They look massive, powerful, and "realistic".
Similar notations go the FarScape Battlecruisers (both Peacekeepers and Scarrans).
2.)
Coolest? I wanted to say I can`t pick a single one, but now I see:
The EA Aurora Starfury is the most interesting and beatiful starfighter. I always loved to see all these little engines allowing it to steer around all ship axes... It made sense, and it looked cool.
I would buy any computer game including this ship model in a heart-beat. (Well, maybe not any, but I would give it at least a deeper look

)
Speaking of computer games, I remember flying TIE Fighter (the real, basic one, not these heavily armed and armored like the Tie Interceptor or Tie Bomber, or even Tie Advanced or Tie Defender) was really fun. Flying evasive maneuvers as hell - a single hit could be your end. (*hit* "Flight System damaged: Repair time 00:13 seconds" "AAARgh" *hit* *boom*)
3.)
I think the design of Federation Starships (Enterprise & co) is most unique, though today, nobody will really recognize this - Startrek is an old franchise.
4.)
The most realistic seem to be the Space: Above and Beyond Hammerheads and the Babylon 5 Starfurys (and also the cruisers, I think)
5.)
Really bad design was the V`ger, (Startrek IV), I think. The Battlestar Galactica Fighters always looked ugly, but that might be a result of the time they were made.