Since you have a Roland XP80, if you want to keep with synthesizers then check out Rolands Fantom range or Yamaha's Motif or MO range, both have good quality organ samples in them that produce the great Hammond sounds. Hammond still do keyboards and rack units but can't think of the name. You could get a rack/module and midi it to your XP80 which is possibly the cheapest option.
If you are more into arrangers then it's Yamaha's Tyros 2, the upcoming Roland E80, Korg PA range, or Wersi, Ketron stuff.

For the best B3/B4 if you are into recording I would stick to a computer and use Native Instruments plugins or other VST stuff.