I use Bob Martin's Antibacterial clumping litter (clay), its £5.25 for a 20kg bag! which lasts about 6 weeks, I tend to buy 4 bags at a time (a great workout when your living in a first floor flat, they're HEAVY!!!)
I've had no problems and it only tracks a little bit, there are also no smells whatsoever, its great
the only other one I've used (because I couldn't get BM one) is tesco's clumping litter which I found to be a bit more dusty although a good price