Well I don't know who will win but I'm debating that Tsunade would win. I know I'll probably say a lot of things that have already been stated but I'm putting it in my perspective.
First, Tsunade has amazing taijutsu. Super strength and speed in on is very hard to counter. Yes Kakashi is faster but there are scenario's that can be thought of where Tsunade can catch up to him. One possibly being punching the ground to cause Kakashi to lose balance.
Secondly, Tsunade has strong ninjutsu. By strong I don't mean a lot of attacks but she has abilities that aid her in battle. One of these abilities is summoning Katsuyu. Katsuyu can spit acid from a long range, heal and divide into many smaller snails. Katsuyu can heal Tsunade while she is fighting. Also, Tsunade has the best medical ninjutsu. As stated by many characters wounds that other medical ninja would consider hopeless, Tsunade can sure with relative ease. Another ninjutsu technique Tsunade has is Creation Rebirth. This technique (even though has a huge negative affect) can in a word, allow Tsunade to regenerate.
Third, Tsunade has intelligence and experience. I'm sure Tsunade will be able to think of something that gives her an advantage in the battle. Also, her experience gives her an advantage by allowing her to to be used to different good or bad situations in a fight.
Fourth, Tsunade has more stamina and chakra reserves than Kakashi. This is proven by Tsunade stating herself that she reserves chakra which is why there is a diamond in the middle of her forehead. Also, many times Kakashi is shown to easily tire if he uses a jutsu like Kamui. There's a reason she is known widely as one of the best Kunoichi, a Sannin and a Hokage. So we shouldn't underestimate her.
