I like an oil based finish on darker woods like Cherry, Walnut and
Ipe. I think it really brings out the grain of the wood and it just
can't be beat. Water based poly does not do nearly as nice of a job
in bringing out the grain as oil based finishes do.

Way back when I finished a really nice set of hard maple shelves with
an oil based finish. There is only one way to describe them...
"YELLOW". I will never use an oil based finish on maple or a light
wood again.

I prefer water based poly or laquer on light woods depending on the
function of the piece. Laquer is by far the easiest finish to work
with and I do use the Deft rattle cans if I can finish the piece with
one can otherwise I buy a quart or gallon and use spray equipment.
For any sort of table top with a light wood I prefer water based poly
for it's protective qualities. It has been my experence the water
based poly will hold up a lot better than laquer. I recently built a
rail for a staircase out of maple with an IPE top cap. I used laquer
on the maple and oil based varnish (1/3 tung oil, 1/3 spar varnish and
1/3 turpentine) on the Ipe. I love the way it turned out. The oil
finish on a wood as hard as Ipe should last a long time. If the maple
gets a scratch, it will be a very simple repair with a rattle can of
Deft.

P.S. When it comes to walnut many mills steam walnut to better
distribute the natural pigments througout the wood making the sapwood
closer to the same color as the heart wood. This has a tendancy to
greatly recude the impact of walnut. If I have a piece of walnut with
sap wood on it I try to position the sapwood on the final piece so it
becomes a feature of the piece not something I need to try to cover up
and blend in with the rest of the wood. Book matching two pieces of
walnut with sapwood can make for a very stunning visual detail in my
opinion.