I had a C-64 and a CPC464 (tape drive). The C-64 I thought was more user-friendly, and had better playability in general as far as games went (looked better, much MUCH better sounds).
The CPC464 had a fast tape drive (compared with the C-64 anyway) and the CPC664's disk drive (with a strange Amstrad-specific floppy disk) was heaps faster. It was also a better programming machine if you liked that kind of thing.
2 good machines, I still prefer C-64 over CPC, and WinUAE over both.