Action = entry level basses. Depending on your luck, you may end up with a pretty good cheap workhorse, or a bass that will require a lot of modding to make it play and sound fine. I owned an older Action bass and it was ok - it had aftermarket Dimarzio pickups and completely overhauled hardware though. Lately I've seen an improvement in this line and I wouldn't mind rocking an Action V-A or a DLX - those seem ok (haven't testem in person though)
Artisan (B5, A5) = the real deal; very nice basses, with quality components. B5 is Cort version of Ibanez SR505, while the A model is top of the line. I have a C model and although I like it a lot, I must admit the electronics are poop - so as long as you aim for a B or A model, you are set
Curbows...some like them a lot, others complain about 'em a lot; the tone is different due to the pickup placement, so it's better to try it first in person.
I haven't got the chance to test the Ts, so I don't know much about those. The few videos you may find on YouTube kind of suck, you can't get a general idea of the quality and the tone of the bass.
Oh, and I would personally stay away from C5H...I had one and the output was very weak and the tone pretty thin (especially considering the woods); after 2 - 3 months of just sitting tucked in its case, the neck snapped and a serious crack from headstock to the back of the neck and further down appeared. So...