In general the Y5V are the cheapest, but their capacitance is typically 1/4 off the specificed value if you run them near full voltage. They are also very unstable with temperature and change value with mechanical vibration quite a bit. They also have very high dissipation factor, which, in general, is good for bypass caps.
I use the 1uf size 0402, the 22uv size 1206, and the 100uf size 1210, mostly the 1uf and 100uf for bypassing. When used with via-in-pad, you can get the size 0402 parts down to about 1nh total mounted inductance