Just to mention a little thing about this who would win discoussion....it the Kilrathi Dreadnought with 22km length ^_^
No realy if you try to argue about the who would win you should consider the weapons a ship uses. Whitestar ships for excample are quite small, but using a gravimetric/antimatter beam. This gives them quite a punch and lets the Sat hit a Whitestar with its great mobility.
Also the SSD is a big ship, but compared to what a Minbarie Sharlin can put out in firepower the SDD has just lowlevel weapons...ok many, but then you just have to destroy the upper structure of the SDD to disable it.
Hope you get the point...who wins depends on many things..other then size.
About the ST ships I have seen here...can you have big battles with lets say at least 10 Galaxy class vessels and still have more frames then a slideshow?