I'm with DarkCide... Genesis 3 RULES.
Now, the deeper part:
I HAVEN'T used the V-amp II YET, but I have tested
the Genesis 3 thoroughly vs. J-Station and POD 2.0
My quick findings (and believe me, I tweaked a lot. I had manuals ready for all the deep-editing on J-Station and POD):
Line6 POD2.0 :
way too dirty/muddy. No decent clean tones. Soldano (Modern Hi Gain) is however decent sounding, as is the Fender Blackface model.
Johnson J-Station :
Much better than the POD, better effects, but with speaker-sim. engaged it becomes bassheavy...not muddy. JCM900 model sounds exactly as crappy as the real mutherf...lover...

Some clean models are very good.
Digitech Genesis 3 :
The best of the bunch. Reacts very realistic to lowering your guitar's volume, has best dynamics and response. Clean sounds can get crystal clean. Blackface model and Clean Tube amp are UNBELIEVABLE accurate and good sounding. Basically it shares the models with the J-Station, but is less bassheavy, has EVEN better effects, looks great and has digital out (which the POD doesn't. Also there's no need for deep editing quirkyness, almost everything is direct available without the use of a PC-based editor. Warp-function really works, it's not a crossfade, but a real morph. I played around with a Marshall '78 master volume-model, but I wanted more bite and gain, so I warped it with
a Dual Rectifier (70% Marshall, 30% Mesa=great heavy metal tone).
I really looked out for how each unit responded to lowering your guitar's volume, and how different guitars sounded through them. The POD (to my ears) made a lot of guitars sound alike... only Strat vs. Les Paul gave noticable differences.
The Genesis 3 shines again here, and leaves your guitar's own tone intact. I think the 24bit AD/DA converters and the 44.1kHz sampling rate help alot here (the POD has 20bit converters and 31.250Hz sampling rate).
Still, If I had to choose between POD and V-amp II, I'd go for the V-Amp II, because of user interface (LED-rings), price and ENGL-model ('
Savage beast' modelled after Savage Spec. Edt. ((my favourite allround tube amp, in case you didn't know yet

))
From the info I've gathered so far, the V-AmpII really is a cheaper and better POD-copy, while the J-Station and Genesis are based on another engine and less but better models.
But between a $300 POD, a $150 J-Station and a $300 Genesis 3, the Genesis wins hands down, no questions asked. I'll have one in october...