Excuse me what configuration/settings do you use for convert MVK to MP4 xh264?
I want the best quality i think , this is actually what i am using but idk if is the best, can you help me please? (sorry for my bad english I speak spanish x'D)
For converting a MKV to MP4, the best thing that you can do is to click the "copy compatible" checkbox at the bottom and leave everything else alone (although you can go to the audio tab and disable that). This will recontainer your MKV file into a MP4 and give you an identical quality output. This will be your ideal solution most of the time.
If your MKV file is 10bit though, the MP4 might not read correctly when you open it in an editing program like Vegas. So in that case, you should convert it to AVI instead.