If you had to choose

[marcusj0015]

I'd go for the subtitle conversion, just because not many apps support PGS subs (like iTunes, and every iProduct evar) Audio transcoding options would be nice, but honestly, with the built-in FLAC conversion, I'm covered, and it's SO easy to convert FLAC to AAC.

BTW, Nero's AAC isn't the best, I'd hope they added ffmpeg AAC conversion instead IF they went that route, but like I said, AAC converions is HELLA easy.

[marcusj0015]

I vote for a MVC decoding option.

MakeMKV doesn't already support MVC? :O

[Romansh]

BTW, Nero's AAC isn't the best, I'd hope they added ffmpeg AAC

I hope you mean fdk-AAC via a libavcodec wrapper. If there's one thing the developers of the built-in libavcodec AAC encoder agree on, is that it sucks.