Vardy is a very good striker. I think Vardy might actually be a better tool to have in a team than Kane because he gives a team a few more options in attack.
The thing is, Kane is very good, no question, but he lacks pace, and so he doesn't stretch teams quite so often, and as the guy expected to be usually furthest forward, this can be mean Spurs can look a bit predictable at times. At time, Spurs have done better without him in the team, and I don't think that is coincidental.
If Liverpool had the option of either (ignoring age) I would have gone with Vardy because pace is such a weapon, especially against top sides.