Falcao has a release clause of 60M with multiple teams willing to pay it, so Atletico have no say in the matter. He may not be able to match Cristiano alone, but get another good winger to combine with Falcao, the combo may be better than Cristiano/Benzema.
The best thing would be for Atletico to keep him since they'd be almost guaranteed to get in to the Champions League again and maybe progress more in the tournament to make the money. But Falcao isn't just a world class player, he's a Balon D'or contender so naturally he'd be at one of the top clubs.
The funny thing is though that staying may be the best bet. All the logic says that the team that he should go to is Barca, but Barca play false 9 with Messi and so he wouldn't fit in. He could go to Real, but he'd have the same problem of competing with Barca(although maybe Cristiano and him together would be an unprecedented goal machine). PSG would be a downgrade in terms of the French league being weaker than La Liga. Chelsea are way off the pace in the Premiership and Man City are a bit of an unstable mess(and 12 points off, Man Utd look really strong now with Kagawa and Van Persie giving real quality). Both failed in the Champions League this season. Bayern may be the best bet, but even then Bundesliga is a bit of a downgrade from La Liga. But hey, linking up with Pep would be great, and they are already Champions League contenders.