PeterF re agricultural? - don't be so sure
I learnt on Bantam at 16yo and am now retired, then let me think, in no particular order :- Panther, BSA Sloper, Squariel, 3TA, Red Hunter, Redditch 350, and others, most of which were finds and rat bikes quickly passed on after resurrection, before going japanese and cars.
I kept the D14/4 a long time but eventually someone thrust what was then a lot of money into my hand. By the time I finished with it, it was 192cc and had an expansion box silencer, weighed 212-lb, shot electrics and a self-destruct gearbox. The CB400/4 was, nice. But was a does my back in caff racer and what the CGT should have been ('only' 37bhp & 33Nm at sewing machine revs)
One reason for considering another RE is plentiful spares.