I agree with Nick.
Rombalds moor G/NP-028 is probably the easiest summit. The car parking area is within the activation zone. The walk to the trig point is essentially flat and paved if you wish to do it ‘properly’.
Sharp Haw G/NP-029 is a nice little summit that feels much higher than it is. There is not much room right at the top but I have managed to use a 30m dipole from there without obstructing the path. I use the route from Bog Lane, there is a limited amount of space for car parking too.
Great Whernside G/NP-008 is high on the points to effort scale, John G4YSS describes the route he uses for his annual overnight activation in his excellent trip reports on this reflector.
Whernside G/NP-004 is another easy summit with high points to effort ratio, so easy it seems like cheating! Look in the summits pages for the quick route - easily takes less than a hour.
Birks Fell G/NP-031 is also not too bad to do but steep in some places.
73, Colin M1BUU