Shampoo - really depends on what you want. Majority are the same.
I used to like DJ BTBM but find it ineffective when the car is filthy. Great as a weekly wash shampoo during the summer though. My current fave is Duragloss 901.
Clay - depends on whether you need mild/medium/aggressive. Can't go wrong with the Megs smooth surface clay kit IMO. I now use Bilt Hamber Soft.