If you want to get get close to a real sax, roli seaboard seems the way to go... it offers so much controll, espescially if you add a breathcontroller on top of the roli...

For sax, i guess the 25 key seaboard rise would suffice? Just put it on top of a pa4x, us ethe chord sequencer for your chord progression and give it a run... i have seen a pretty impressive sax demo by Marco Parissi, he was using a Sax VST from SWAM...