What seat do you choose on a bus?

I try to find a spot in the back that's empty so I can sit by myself, until unfortunately obnoxious people have no other choice but to sit next to me. If all seats are empty I just stand in the aisle like an idiot until someone offers me a seat. .3.'

Preferably somewhere near the door or near the driver. If not, I'll try to get a seat at the back.