Canon wise, Star Wars just plain loses in this section of the versus debate. The reason is well...... ST has more and better Super Weapons.
Compare:
SW: Death Star I and II. Massive, around 120km. can blow up planets through a chain reaction. Both were easily destroyed by fighters firing only one too two shots from a weak weapon.
ST: Lots.
1. Trilithium Torpedo. Can destroy entire Solar Systems. Size of a person. Very fast moving. Moderately hard to take out. Federation knows enough to make their own.
2. Dooms Day Super Weapon. around a km in size. Cuts and eats planets. never misses. fast. Very hard to take out. Federation has been studying the remains of it for years.
3. The Temporal weapon ship, fast, nearly impossible to find.Very hard to defend against or take out. Can destroy multiple entire species with a single shot.
4. Xindi Super Weapons. The First could burn/cut around a km wide and one very very long (100 km I think) and km or two deep trench and was around the NXs size. Number 2 could blow up moons and was around the size of a shuttle. The Third was bigger than the NX but still under 10 km and could blow up planets. First is a unknown in taking out. Number 2 is mostly unknown, but it did just fine in the area of around a mostly blown up moon but other than that we don't know. The third was tough enough the three Xindi races plus the NX failed to take it out until the NX crew managed to get aboard it and set multiple charges all over the inside, losing a few people in the process.
Those six I mentioned are a mere handful that I can remember off the top of my head. Needless to say most if not all of ST's super weapons are as powerful or more so than SW's Death Star, and are usually smaller and harder to take out.
