This question comes up periodically. When I researched it, to arrive at some decision, I discovered that Wico was long off the market, Yellow Jacket was basically out of business, Penguin was Out of Stock indefinitely, and there was rather mixed opinion about the wooden flatbed one or any of the Northern Freight solutions. I asked a collector and local operator, who still used one of the old Wicos. He told me that probably the best one still around was the one that (I think) is sold by Marco. There are also two versions of it sold on eBay by a regular seller, one of them appearing to be identical to the one Marco sells, and the other derived from it but having some custom mods. That is the one I got, a link for it shown below. I have not really had occasion to use it yet, but wanted to have a decent solution like this on hand. There are two possible improvements that come to mind: some sort of cushioning for the handle, to make it a bit kinder for the user, and I think I'll be draping some cardboard across the flat support surface, to avoid any rough metal interaction with where the game underside makes contact with the dolly. That would sort of address a "pro" of the ones that have a plywood or rubberized lifting surface.
ebay.com link: Pinball Machine Dolly Lift Cart NEW DESIGN LIFTS 2 HIGHER
The pinball skates have their uses, but won't attach to all game legs.
I never heard of the escalera until now, but am glad to add it to my reference section. Rather pricey, though.
