While it is true that there are a lot of video converters for Mac, for performance and reliability I have always used Handbrake. It is not the prettiest at all, nor possibly the most practical, but it works wonderfully because the obsession of its developers is to make it as efficient as possible, something they achieve with sufficiency.
Faster
With version 0.10 -it seems mission impossible to reach 1.0- we get new video codecs to the last (Intel QuickSync, H.265, VP8, etc) as well as new filters, but perhaps the most important novelty is the implementation of OpenCL scaling. This option can greatly improve performance on Mac with powerful graphics, but it seems that at the moment it does not work as well as it should.
On an aesthetic level, we still do not important changes in the app. While it is true that one more look would be appreciated Yosemitero, It is also not less true that if you have to prioritize between good performance and appearance, I prefer that the application fly on our Macs. I am the first to value the appearance of an app, but in a video converter a excellent performance and flawless conversions, something Handbrake has been doing for years and does not usually disappoint.
For those of you who don't know it, it is a totally free app, Open source and with a fairly respectable community behind it that is usually quite quick to help with any problems that the application may present when converting videos.