i used walker in 1/04 and randy's in 1/05.
randy's is less expensive, plus they seemed to charge days on a 24 hr day, so for example 3 p.m. sat to 3 p.m sun was one day, whereas walker considered it 2 days (based on my pricing research for the 1/05 trip, things could have changed).
both
ecv's were very nice. the model i got from randy's had several more pieces, and as we were staying mostly off site and using a car trunk to transport it, it was a little bit of an issue, but not too bad.
randy's came right away for both drop off and pick up. had to be done in person, and since the ecv had more parts than i was familiar with from the walker rental the previous year, i was glad to have the dismantling/assembling shown to me in person. i remember having trouble dismantling the walker ecv the previous year since it came fully assembled and dropped off at bell services at pop century. i'd printed out directions in advance, and it came with directions, too, but they weren't clear enough and i got stuck on the step where you fold down the tiller. a passing worker who was emptying garbage cans in the parking lot helped me figure it out. took him awhile, too. dropping the ecv off at bell services was very convienent, but as i said, randy's did come fast and when promised.
walker gave me a shower cap for the controls for the rain, randy's made me sign not to use it in the rain.
from walker, i was able to rent for a separate battery charger to use in the hotel room at night so i would not have to assemble the ecv to bring it into the room (i was using a car then, too). randy's did not have that option for the model they'd given me (unfortunately) but he said i should ask about it at the time of the reservation next time, and they might be able to rig something up.
for me, there are definitely plusses and minuses to both companies. on the whole, both were positive experiences, but with differences. i'm not sure what i'll do for my next trip.
-dj