I would reccomend the N810 (which i have myself).
A friend of mine have a 16Gb iPod Touch, and of course i've been comparing them.
This is at least a list of features the touch does not have, but the N810 have, which i find important.

It has full Flash 9.
Can connect to internet via phone (bluetooth, which the touch doesn't have at all).
Has really good speakers.
Has a kick stand.
Larger screen.
Supports USB OTG.
More apps.
UPnP (correct me if i'm wrong, but i never found any way to enable/use this in the iPod Touch)
GPS.
IM.
Full Qwerty-keyboard.
Better screen outside. Tested this outside in bright sun. And here in Norway the sun can really be bright when up in the mountains with alot of snow around that reflects more light.
Memmory expandable to what you can afford (and how much space you have in your pocket for memory cards).
Possible to change battery if you have one extra.

For me it's good enough reasons to get the N810. Especialy as the screen is better that booth N800 and iPod Touch.
Anyways, hope it helps