I think for wi-fi and web browsing you really need to go the whole hog and get a good powerful 10" tablet.
On the smaller pocket sized gadgets you pay over $100 just for wi-fi dongle and 256MB of RAM, like this:-
Window N5 Pro2 , Android 2.1 , G-sensor ,5 inch, 8GB , wifi adapter freeshipping [N5-Pro2-elite] - US$113.00 : JTSHOP Online
I would be inclined to get 2 devices,

a bigger ipad sized device for web and wi-fi and a smaller pocket sized device for carrying around without the wi-fi dongle sticking out. :roll: