Electro Harmonix Lester K Rotary Simulator (For Keys and Guitars)
It is quite a bit smaller than the competitors and fits neatly on top of my Nord. The foot switches are momentary and very light so they can be operated by hand. This was not the case with the Vent although that had a remote option. It's true stereo in and out with true bypass which is another plus. You can also adjust the Rotor/Horn balance which is great for removing some of the treble and it also has a volume control on the output so you can crank it up for solos without risking overloading the inputs.
Finally, the Lester K sounds more like a Leslie in the room than a mic'd Leslie and I think that why I prefer it to the Vent. It sounds great with the Nord Electro 5D using Clean B3 and no effects. I think different organs suit different Leslie simulators and you really have you try each one till you nail your sound. At the moment the Lester K and the Nord E5 does it for me! Well done EHX!