Tier 2
1. Darth Maul 4
2. Darth Vader 5
3. Obi-Wan Kenobi and Anakin Skywalker 7
5. Qui-Gon Jinn 8
6. Luke Skywalker 12
Obi-Wan and Anakin are pretty much equals in ROTS. I would give Obi-Wan slight edge with lightsaber due to performance against Maul and also Anakin is reckless. Anakin has edge on force knowledge.
Anakin full potential is most powerful of all Jedi and Sith, stated many times.
Luke is son of Skywalker and I think he could have been almost as powerful as Anakin. Showed how strong he is by training in very short time span to face and beat Vader.
As Obi-Wan and Vader are pretty much equal when they older, this means younger Obi-Wan and Anakin have much better lightsaber skills.
Qui-Gon Jinn is strong with the force but his lightsaber skills are not the best.
Darth Maul is clearly most superior lightsaber of tier 2 and he is only an apprentice at this time. This makes me think he can become very powerful and high tier 1 for sure.
Dooku is underrated. He matched Yoda and took on Obi-Wan and Anakin at same time.
Windu is number 1 with a lightsaber no doubt. Yoda and Sidous are equal and more powerful overall combining lightsaber skills and force knowledge.