Different filesystems have fairly negligible effects on the performance of MySQL as it doesn't have huge demands on them. XFS is often recommended for how well it handles large files and large file deletions, a combination useful for video storage (e.g. MythTV), but rather less of an advantage for MySQL which doesn't delete files much. Ext2/3/4 are also good performers, as is anything else modern and current in Linux. The +noatime option will positively affect your actual disk traffic, which I have measured, but I couldn't measure any difference to MySQL.
Generally, if you have enough database traffic to have to worry about the filesystem under MySQL, then you should be looking at high-end dedicated hosts in a co-lo, not Amazon EC2.