I currently use a JB-04 and can give a good recommendation for it. It breaks and jumps very well while also being quite attractive. If you don't choose Samsara, I still recommend their break tip above any others.
If you're looking purely at function for breaking, it's my opinion that the Predator BK2 - ugly as it is - with a Samsara tip may be the best. I've tried many.
I don't really like LD shafts for playing, but I find for the break they improve consistency in smashing the head ball exactly where you want to.
I'd certainly agree on the Samsara tip,,,,never tried a Samsara Break stick though,,,,,,,,in general I believe Samsara cues are at least as good as any from the reviews I have seen,,,,,
I just received my JB04 from Martin (jazznpool) and am very impressed with it. I had been using a wrapless BK2 with phenolic tip for about six years, so the leather wrap, Samsara tip and different feel of the cue altogether took a couple of breaks to get used to. However, I am very glad I bought mine and would recommend them to anyone. As long as you have a good break stroke, the Samsara packs plenty of power, feels and looks great. Don't get me wrong, the BK2 is a great break cue (I am still keeping mine), but I think the Samsara breaks just as well, and looks much nicer to boot.
I would also highly recommend Martin as a seller if you are getting one.
I got a jb-04 from him as well and I love it, breaks great and jumps with ease, I recently just sold mine to another cue I shoot with and he feel in love with it. I plan on buying another ASAP. Trying to pick up the jb-02. I may matched mine up with a bk2 shaft and samsara tip, can I say it was amazing..