I’m a big lump and for me 12s is a revelation. Just because you have the power doesn’t mean you have to use it all but for me my 12s set up runs cooler than my equivalent 10s at the same settings.
Don’t ask me why because I have no idea. Not my area of expertise but hill climbs with the 12s and the motors are cooler. Theres some mathematical and physical electrical wizardry going on but its above my paygrade so I just go with what actually happens.
12s all day long.
If the amount of current you are drawing does not approach the cell ratings, then the 35E will be better. Typically in esk8 we run current values close to the cell ratings and so 30Q are almost always better. Almost always. If you’re over 8P you should reevaluate the best cell for your needs. Or over 6P on a single-motor. It still might be 30Q, but it might not be.
Once you get to the 10P depths, 30Q is almost never the ideal cell anymore, unless you’re drawing 100A or more from the battery.
based on what you posted, my advice would be go with 10S. It tends to be a more dependable option than 12S where most ESCs are concerned and at 10S voltages you’ll be limited to a lower top speed which will force you to extend the range because watt hours are watt hours no matter how you slice them.