MySql or postgre?

Hello all, i hope you can help me on this one. I'm kinda recent to php and mysql although i've been working in programming for a couple of years. i'm also new to mysql and postgre... i've been using mysql and i find it fine, but i saw some posts were it says that mysql is not that good. i know a few of you are experts in this matter and i would like to hear you about this. is postgre better more efficient, does it needs more recurses, is it faster, how about sql... are there any lacks on both of the data bases? thank you all for helping me!!