I have used one like this for around 5 years without issue... cheap, no light board required and holds 3 normal bikes, it was only £40 when I bought it. (might have been Hollywood brand)
I do prefer roof mounted bikes and have recently switched to automaxi gutter style racks on thule bars, these seem a solid combination too, and you don't see them wobble about as you are driving
The most convienient is the cheap (£80 - 100) towbar bracket mounted ones (not the ones that clamp to the towball) they are basically 2 L bars you can keep in the boot, but you might need a light board too depending on your car ... and a towbar of course.
If you go for the high mount one it can rub against the top of your bumper/boot on a hatchback so I used to put a cloth or foam padding there to stop marks. some people do the same where the hooks attach but I never felt the need.
I use one i picked up at sainsburrys last year while doing the weekly shop for a mere £14 , bit of a pain to setup, but for the price, i cant afford to maon too much.
A few points to consider. My mate Jock (very old fillet brazed Saracen), did a hard braking manoever and his roof mounted bikes carried on down the road! Car park height restriction barriers. Low trees. I believe roof mounted systems lower your miles per gallon quite a bit. PC Plod takes a dim view of rear mounted bikes covering up plates etc. Pretty sure that I remember reading that Pace (and others?) say that a roof mounted rack that requires the front wheel to be removed will void the warranty. Having said all that I have used both types with no worries. My parents have recently had a tow bar mounted system that they swear by.