Best app for MKV building?

[gs684]

Hi all:

I have a large library of movies and TV shows. They are all in MP4 H264 format, with some older ones being in MPEG-2 format. They all also have separate .srt subtitle files.

I would like to do batch conversion to MKV format (without any recompression), where I can mux the video and subtitles into one file and edit tags and chapters.

What is best app these days for this? Please note I'm looking for a GUI program; no command line stuff.

Thanks for the help in advance!

[Subtitles]

I use MKVToolNix GUI. Just add the video and subtitles in the "Add source files" and then "start multiplexing". Make sure you selected the output folder.
It is really fast. You can also create chapters if you want.
I haven't done any batch processing as I prefer to check each completed task is perfect.