REAPER is awesome! It has been my DAW of choice for 15 years now. It opens instantly, it's very fast and snappy and it practically never crashes.

I particularly like the concept that everything is just a track. In REAPER, tracks can be arbitrarily nested, they can contain all kinds of items and you can route signals between them.

You need a group? Just make a track and add other tracks to it.

You need a bus? Just a make track and send to it from other tracks.

You need an instrument track? Just add a VSTi to it.

You need a MIDI track? Just add a MIDI item.

In most other DAWs, these are all different things, for no good reason IMO.