20 years+ of experience including seeing what others are using and there experiences.
I would go with one or two -
Grass Hopper or Patterson
just check their own websites. Your location may be a deciding factor. I know grasshopper will come to you but I do not know about Patterson.
The very cheap China made products you see on ebay are fairly unreliable.
I have had had experience of the PowaKaddy which was bought out by Electrokart (Voyager) but no experience of that particular manufacturer. They should have a better controller than the one fitted to Powakaddy their motor/ gearbox combo.
Worth making sure you buy a model suited to your weight. The uncushioned tractor seat on the grasshopper model gives you better stability on slopes than the cushioned seat but you have to absorb the bumps a bit more.
Whatever model you buy do not exceed the slope rating, avoid steep slopes if possible and try to 'zigzag' up hills.
We have the Grasshopper Junior Classic for rentals, they have been good.
Some of our members have now gone on the buy them, quite a few members have the Grasshopper Senior Pro buggies, I think they are good all year round buggies as you can get a decent cover for them.