Well you have to ask your self how often you will wax/seal your car? This may help your decision as far as durabilty is concerned. Shine on white is just too subjective as to what product will give the best results. The reason i vote for Zaino is your situation, is that I have used Z2 on white with spectactular results. And again, the longevity of zaino's durability has been proven itself over and over with many. Z2 would be great if you only want to wax/seal once every few months or even longer.
I have also used NXT on a white maxima with outstanding results. A few people that i have used NXT for are still beading well after 3 months. So durability is also good. (some people's results with NXT have varied.) Currently Im using NXT as a winter wax right now...reason being is that it is VERY easy to work with and doesnt require the patience of a looong cure time that Zaino will need with the lower temps of winter. I literally use NXT on my car about once every 2-3 weeks because its so easy with great results.
Actually for my car's blue, i think the INITIAL results with NXT are better than Z5 and Z2 but it seems NXT's look fades away more quickly than Zaino. (That's one reason why i use NXT every 2-3 weeks is too keep the "look" it gives.)
Do i think Zaino will give you a better shine and durability for WHITE than NXT?? Yes
Hope this helps, and just remember this is my opinion.
Cliff notes: Use Zaino Z2, if not, then I suggest NXT as an alternative.