I've looked to see if this has been mentioned before but can't find it so here is my wish.
The ability to import Video so I can write to it.
I really like using Power Tracks for mixing and my VST mangling experiments. It's one of the programmes I first bought when my old faithful Atari started acting up. I bought Sibelius for my notation needs along with BIAB 2007 for backing tracks and Power Tracks Pro Audio for mixing and burning CDs etc.
I have Sonar LE that came later with my digital piano and I've packed it out with free and paid for VSTs but I haven't really gotten into it. Power Tracks is more intuitive for me and is laid out clearly, so to have the ability to score video and mix with my weird experiments would be just great!