"Pay what you like" is a
terrible business model for most applications.
Remember that Radio had an established fan-base who was already sold on the quality of the product. If a previously unknown band had tried that, nobody would contribute before hearing the music-- and then, after hearing the music, I imagine only a very small percentage would remember to go back to contribute.
As for freemium, there are significant drawback to that, too, that you need to keep in mind.
First of all, you need to make sure that your "paid" version has enough added benefit that it will get users to actually convert. If not, you end up (in the best case) with traction but no revenue. In the worst case, you end up with a lot of very demanding users, placing a support burden on you, with no realistic hope of conversion. If you're not sure if support on your app scales, be careful offering a free version.
In short: figure out what your product is worth to your customers, and charge for it. Don't be afraid to price it high, if it actually provides sufficient value.
As Patrick already pointed out, recurring revenue is a god-send, so a subscription model is brilliant, if your product lends itself to that kind of purchase.
Remember: the goal is to maximize LTV, and minimize CAC.