always used paper maps, but tired od carrying loads round on tours, so i am gonna give in to the modern world.
looking for a large screened gps. what is the best.

nowhere near the best but these are quite good and have a big screen, budget a few hundred quid more for accessories

http://www.barcodesuperstore.co.uk/trimble-yuma-2-t7148l-h3s-00-barcode-rugged-tablet-pcs?gclid=CPzo96nXpL8CFQEUwwod7BIADg

well you said regardless of cost

Tony if you’re looking to use it for touring i’d look for something that runs on AA batteries rather than needing to be charged via usb everyday.
AA’s are easy to pick up, so you dont have to worry about running out of power.

Of the ones I know about have a look at the Garmin Oregon 450.
Big brother of the Dakota 20 that i have (cant fault it), but a larger touch screen to go with your gorilla sized fingers.

You can buy the units on there own and then get 1:50k maps via ioffer

Another shout for an Oregon.

Decent screen and battery life and runs off AA batteries.

I’ve had a Dakota 20 (just sold it to richpips) and like the bigger screen and slightly faster performance of the Oregon 600 I now use.