I was having a discussion about the effectiveness of battleships since WWI with a limey bastard. The subject turned to displacement and of course the Yamato and her sister ships came up. Someone else chimed in about the second biggest battleships ever were American and I said "nope, that distinction goes to the Russians". Everybody was like "WHAT" (chicken neck black woman move and everything). I said since the guys said "EVER" then the Russians built the second biggest battleships "eva", post WWII of course. Then someone said if we were going to straddle "eras" then we might as well bring nuke powered battleships and "Star Wars". To which I said "Star Wars? Why Star Wars, Star Trek would kick their ass!". IT WAS ON!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! (black chick taking off her picking rings and chains getting ready for a throw down!).
We went back and forth a little bit with every Sci-Fi contender we could think of, excluding cartoons, and came down to two groups: contenders with sheilds and contenders without shields. Fair or not we excluded all non-shield contenders, Battlestar Galactica, Serenity and Babylon 5, because they can't defend themselves. Babylon 5 did have some ships with shields if I can remember, so they straddle IMO plus nobody else knew much about that show. Actually, there wasn't anyone else who knew much beyond Star Trek and Star Wars. I know Star Trek guys stated how much energy their weapons and sheilds are capable of, Mega or Tera Joules, but I can't think of anyone else who did that so getting technical may or may not be possible unless you scower the internet for tech data but this I'd prefer more of a "off the top of your head" discussion (if anyone dares the shame of participating). We also didn't include certain movies that didn't have sequels (5th Element, Wing Commander or Independence Day), nor crappy series (Andromeda, V, Space Above and Beyond and Earth - Final Conflic). Also excluded out-dated stuff like Space 1999 and Buck Rogers.
So......
IMO Stargate SG-1 would take the cake with the Ori and Asgard ships leading the charge. Ships without shields would get instantly wiped out using only "armor". Heck, the original Yamato could take out a space ship that only used armor if it would get close enough.
Don't even get me started on the Wave Motion Gun. Anyway, Star Wars, Star Trek and some Babylon ships had shields as well but those shields proved to be useless when ships rammed into each other, as was shown in several episodes and movies. The Ori and Asgard, including the Asgard upgraded Earth ship, would withstand a HUGE ship ramming them then harmlessly being destroyed, like the jet fighter vs mothership in Independence Day.
For that reason I go with Stargate SG-1.