The water based will not crack. You could use an oil based finish, but will not gain anything by it, other than the clarity they provide vs. a slightly milky finish from the water based. Water based finishes have really come a long way in the past 5-10 years and really are just as durable as oil based, even more when it comes to resistance against solvents. An oil based finish will be impacted by any spilled gasoline or oil, while a water based would not be impacted to much degree at all.
If you were going to be using it outside, then I might suggest a spar varnish, because of it's flexability and thus ability to withstand the movement of the wood due to the outside elements, but since this will be an indoor piece, then a poly is fine.
Wax would only make the top more slippery and would not add any protection or other value.
-John