So part of the run will be outdoors?

I'd put in 50, some of the bigger inductions require that. Ampacity for that is going to require #6 or #8 depending on exactly what you're going to use. I'd also recommend running a grounded conductor and a ground (some cooktops need the neutral). As Joe aludes, if some of the wiring is going to be outside it needs to be rated for sunlight or you have to use wiring in conduit and possibly damp/ wet locations.

The wiring is all indoors, it will run along the ceiling of the basement. This is the range:

http://products.geappliances.com/ApplProducts/Dispatcher?REQUEST=SpecPage&Sku=JB750SFSS

If it is all indoors and installed where not subject to damage you can use 6/3 NM copper or 4/3 aluminum for your 50 amps. Both with ground of course. (4 wire required by code for your installation).

This post was edited by joefixit2 on Tue, Oct 14, 14 at 23:08