Tracktion T7 the latest upgrade, like T6 is also free - hard to argue with that as a proposition. Tracktion have long been an advocate of the single window approach to a DAW, its a simpler to use interface and makes it an ideal starting point for new DAW users. Added to that is the multi-platform support, Windows, OS X and Linux.
New in T7
Tracktion T7 is available for free download now, with discounted upgrade paths to the full WAVEFORM daw.
Cursus Iteritas Percido, Fractio Solum, Terci Ruina and Sinc Bucina
2hp seem to keep packing a load of features into their tiny little modules