Having a pretty heavy electronic/electrical background and being in the electrical industry for 20+ years I get where you're coming from
A rough rule of thumb would be to go one or two sizes smaller than what you were using in Kanthal. So if #28 is what you're using in most kanthal builds, you'd probably want #30 nickel.
Personally I just try sticking to #28 and #30 for the most part just because they're the best balance between physical strength and being able to keep coil sizes down to manageable levels. Anything thicker and coils get obnoxiously huge, anything smaller and they're just too flimsy for my tastes.
Another thing worth looking into are twisted kanthal/nickel builds. I'm not familiar enough with them to give any solid advice, I'm just starting with those types of builds, but I think I'll take the time to play with them while I'm on vacation as of tomorrow.