Generally speaking, a lot dont use data, although almost all have features which do use it.
Tomtom doesnt use data for navigating, just for traffic etc (same as others).
Tomtom doesnt use the internal GPS without a hack however, which means you have to reset the GPS device in the tomtom menu every time you start it up.
It also uses increased power consumption due to the way the hack works. Add to that, theres no support, since the
N95 isnt supported.
You could try nokia maps, its not great featurewise, but you can download maps for your country, rather than downloading them over the air. You do have to use a bit of data when searching for postcodes etc though.
The ones that do not need data to navigate are:
Tomtom
Garmin (not available for 8GB unless you hack it, since its supplied on memory card and locked to it).
Copilot
Navigon (but no sign of any updates for a long time)
Route66 (I dont like the routing, but some say its ok)
Sygic (just not good enough yet imo)
Navicore (old version - supposedly an update soon).
Id go for copilot if I were you, as I said, theres a much better review coming out very soon.