The new creative tips called performance are excellent. There's no contact area and you dont need to thin them before you apply them, you just stick them on and blend, and they really do blend quickly and effectively. I would recommend these (that is if you can get some creative stock!)
Also, I must confess, I bought some cheap tips off e bay, just for use on the nail trainer. They are poor quality but because they're a bit flimsy they blend really easily, so if youre after some to practice you might want to give them a go since they are less than £10 for 500 tips, I wouldnt use them on real hands though personally.