Airtonics FHSS-2 & Futaba FASST are both technically better than Spektrum's DSSS (DSM & DSM-2) current offerings.
Spektrum's DSM-2 (DSM-Pro) is the only one I'd ever consider in that line.
KoPropo is very nice as well & from what I have seen is very fast stuff.
I'm currently running Airtronics.