Armor drivers should almost always be Engineers, but we think it's a good choice for Commanders as well. Sure, the Commander can drop a repair crate onto destroyed assets, but this also gives the offending Recon saboteur free ammunition if he's still lurking around. It's nearly always better to simply repair the assets yourself, instead of taking vital fighting personnel out of the battlefield.
If you spend 100% of your time safely and courageously tucked inside of a vehicle - you may consider skipping the Squad Beacon altogether, burning the unlock on another piece of equipment instead. Engineers have several can't-miss items in their kits - but also some ho-hum fare. Unfortunately, to get the upper tier goods, you'll need to unlock everything underneath it, so you'll need as many unlocks as possible to power through to them.