#2 PSG

At 33, Cristiano Ronaldo can give Real Madrid one or at the max two more good seasons. Beyond that, they need to replace their superstar. PSG's Neymar would be a like for like replacement both in terms of footballing ability and global popularity. At 26 he has age on his size and Real Madrid can look to build their team around him for the next few years.
Conspiracy theories abound about Neymar's desire to move to Real by using PSG as a transit. Barcelona would have never sold him to Real. True or not - Neymar needs a bigger challenge than what Paris provides. For Ronaldo, it would suit to move to a big money project where he can take center stage.
The stumbling block would be PSG's Qatari owners. Having only signed Neymar a year ago in a world record-breaking transfer, it is unlikely that they will let go of him so soon. Ronaldo plus a good amount of money might be required to tempt them. But that would hurt CR7's ego no?