Going back to the post, I have driven a Gen3 Alphard when holiday in Japan.
In my opinion it is much more modern and refined then Gen2, you get better chassis, seats, technologies, looks (personal), etc...
The only downside is the cost, I think they start from £30000 in the UK, where a decent late year low milage Gen2 maybe around £20000.
If your budge allows then get Gen3, otherwise Gen2 is still very good.
If you search TM Trading which I think have a London showroom, you can probably have a look around and get test drive, etc... and experience yourself. They should have a few Gen3 Alphard/Vellfire.