The best clippers are Oster but they are quite expensive. I had an Oster which Iused for trimming my scotties and other dogs, so they worked hard. I've had a couple of Wahl, which were hopeless for any heavy duty work. I gave my Oster away, I wasn't intending to get another dog, but then Dylan came along. I bought these clippers from Zooplus, they had good reviews, and as there is only a small amount of clipping to do on a spaniel (if you're not clipping the coat that is), I didn't want to spend too much. I find them very good, and you can buy Oster blades to fit if you want.
It all depends how much clipping you need to do and how much you want to spend. There are some cheap clippers on the market which are rubbish, but these seem good value and certainly do the job.
Lesley and Dylan