Best free stand-alone software to create midi drum patterns?

Hi BB friends.
I am looking for recommendations for the best free stand-alone software to create midi drum patterns.
Please fire away.
Many thanks.

See my thread Software to create BeatBuddy (BB) beats, songs and patterns

For simple, I really like Hydrogen. Once you’ve set up a BB-compatible drumkit everything is fast and intuitive. There are two main limitations…(1) you can’t import MIDI (so it is a beat builder, not an editor) and (2) you can only export the entire song as MIDI, not a selection of the song.