In terms of general picture quality, LE scores higher, especially when it comes to OTA SD content, where the picture is sharper and colours more vibrant. However CE continues to show great improvements and recent nightly builds bring the quality much closer.
This is a settings issue and not intrinsic to CE/Leia. I had the same experience - but it was solved by disabling all SD formats in the whitelist, or in the latest versions - simply not selecting any whitelist settings. Its been discussed over at the CE forum before.