Do you really want 10 gallons of the same beer? Or rather 2 different ones at 5 gallons each?
I used to do 10 gallon batches, but over the years I started to appreciate having more variety. So I now often brew two different 5-gallon batches, back to back. There's only one cleanup.
If you want to brew 2 IPAs using different hops, you could brew a double-size batch and split the wort before adding the late boil or whirlpool hops.
If you want to save time, think of using a second heating source and kettle, so you can heat your strike water for the next batch, or even start the mash, using a 2nd heating source while boiling/chilling the current batch.
In that light, I really like induction (3500W),* it's fast. Now for just heating water (no risk of scorching) anything would work, even a big bucket heater, or a gas burner.
* Induction
does require a kettle that's
induction capable.
Mind, a kettle being non-magnetic doesn't always mean it's not induction-ready. I have one kettle like that, it works 100% fine on induction, although a magnet won't stick to it. So you do need to make sure the kettle works on induction if you go that way.