SACM
I don't have NTL telly
But seriously, I'd still want SACM as they're dedicated to the job and not (always) made on the cheap with cheap components by STB manufacturers like Pace. Though I do like my Motorolla Surfboard much more than those Ambit ones, but that's just a cosmetic thing.
On the other hand if you do have digital telly, a SACM would involve using a splitter on your coax (one to STB, one to SACM), and that would reduce the signal to the SACM and might cause problems. Though I don't know if that's what's happening inside a STB anyway, if so then it makes no difference either way (but if you dropped the telly you'd benefit from a STB in terms of signal
).