Thermal is for drivers. But it's pointless now a days with Javelin's out the ass.
Javelins don't bother me that much, but I still run smoke just to be safe and break any kind of lock on. Kamikaze C4 is way more annoying IMO. People love those little things.
I run with proximity 24/7 nowadays. Reactive would be good, but I can do without it most of the times when fighting other tanks, besides I had my tank stolen a thousand times when I'm repairing the armor. On the other side I just can't fathom trying to capture a flag without proximity anymore...
It would be great if I could run thermal/reactive or thermal/autoloader but I'm playing mostly with randoms that I can't trust and I'm just too much paranoid now.