As a mainly Cubase user (i use Sam ProX3, Sonar Platinum, S1 3 a little as well) i recommand the following:
1. There is no need to buy another DAW in "panic" mode
2. Write down (best in MS excel or open office) in a silent moment your "personal" important functions you really need, classify then
in Must have, Could be and nice to have
I'm sure you're gonne need some time, that will be a long list!
3. Then insert some other DAWs and proof if they have this function, and IMPORTANT, how well is this implemented !
Note: Some users use Cubase, S1 3, Sonar and so on and can surely help.
4. Write down some functions that other DAWs have, but Sonar not (not easy, but we can help :)
5. Then decide, and be sure, you have time to choose!