I took a punt on a cheap ‘rassine’ branded 3.5 years ago. Its a fork axle mount version. I think its sold on Amazon under a different name now.
I’ve used it on average twice a week across three cars since then and its been fine. The little suction pump seals fail – I’ve replaced two, but they all seem to be a standard size so I just bought whatever was on ebay for £10.
You can also have trouble getting them to exert the suction force when the rubber is hard in cold weather (mine is kept in the car boot) but keeping them indoors for and hour before use deals with that.
In use, its more stable than my old thule 591 setup and has stood up to 6 hour trips to the lake district.
I’m fastidious about cleaning the body panels and suction cups on every use to make sure my pride and joy doesn’t fly off down the road. To make this easier, I put together a little kit with a spray bottle and microfibre towel for cleaning and moistening the suction cups.
I’ve got no real reason to go back to traditional roof racks at this point.