Personally I use Pavtube MTS/M2TS Converter to handle my mts and m2ts files,
before using it, I've tried many ,many different sorts of converters,
virtually all of them can transfer mts/m2ts to other common formats, but
always bring problems one or another, like terrible conversion speed, audio
and video out of sync, etc. This one does not have these issues, so it won my
appreciation.