I have a Yakima heavy duty rack that I like a lot. However, it is hard to get on and off because of the weight. It folds up nicely and stays on my car all summer. My spouse doesn't like it because it is so heavy.
Muriel, we also have a rack that looks like the rack in your first link. It is much lighter than the Yakima and I can easily use it myself. However, those center thingies that hook over the top tube of the bike are fussy. They sometimes are difficult to get up and down. The foam covering on our's moved and the metal ended up scratching my bike. At least it was my ratty hybrid. But the scratch is big and ugly. I do not like the rack other than the fact that it is light and easy to store. But my review is colored because of the scratch.
Trek Madone 4.7 WSD
Cannondale Quick4
1969 Schwinn Collegiate, original owner
Terry Classic
Richard Feynman: “The first principle is that you must not fool yourself and you are the easiest person to fool.”