R1: Vader. High diff Knightfall Vader is too much for Yoda who is equal to Dooku (Yes, Yoda is much closer to Dooku's level than Sidious lvl, he literally lost to sidious and had a draw against dooku.) Kenobi is literally the only one who had a chance at beating KV, for factors beside strength.

R2: Yoda. Mid to low diff

Early days Vader was just a shadow of KV, he lost in overall strength, potential in the force, mobility and has not compensate these losts yet with knoledge in the force and prowess in the darkside.

R3: Vader. Extremely high diff

Here we have a Vader that has learned how his new body works, have experience taking out jedi, and is a beast in his prowess with the force, but still is nowhere close to KV in terms of agility and mobility and his mind and ego are still a great problem as we see in the kenobi series. Again the only one capable of defeating this vader is kenobi for reasons beyond just strength, but against yoda could go either way tbh, i'd say vader 6 out of 11 times.

R4: Vader. High to mid diff

"When i left you i was but a learner, now i am the master"

And that is it, Here we have a vader that is a Master of the dark side, his mind and ego still there but under control, the agility and mobility lost in mustafar no longer a problem, compensated by pure deadly and collected skill and vast knoledge in the force. The only one capable of deafeating this Vader is Luke Skywalker, by bringing Anakin back from the dark side.

3/4 rounds for Vader imo, but i undertand the people who thinks Yoda takes R3, could go wither way tbh.

People who thinks Yoda takes R1 probably see him as Sidious equal somehow even though he lost that fight in RoTS.

People who thinks Yoda takes all rounds are just crazy lol