Soundwise
AIR DB-33 is awesome. Definitely check it out.
http://www.airmusictech.com/product/db-33
+1 for the DB-33 Tonewheel Organ Simulator. Came with my AIR instrument collection. Like the Velvet is to a Fender Rhodes, these organ sounds are realistic.
Never had the opportunity to play a real B3, or any of the other VST's mentioned here, but this thing sounds better than any organ samples I've ever heard in a synth.
DB-33 Tonewheel Organ is a virtual organ that recreates the sounds and controllability of classic tonewheel organs such as the Hammond B3, and the rotary-speaker cabinets they are often played through. It includes 122 preset sounds plus an extra-realistic convolution rotary cabinet and tube overdrive emulation. The rotary-speaker cabinet can also be used as an effect in its own right on an audio track.
Trial version available.
Edit: was curious to see if the installer loaded any factory sample content, like a few of the AIR products do. This one does not, in fact the installer is relatively small. So if it's not modelling, it must be wavetable based.
There are other products from AIR that do not appear to be sample based, so this could be some combination of their tech. These are Hybrid 3 (basic waveforms and wavetable), Loom (additive), and VacuumPro (virtual analog).