I went to both about a month ago, Newquay were very good and let me fly a couple of practice ILSs, they even switched the runway so I could fly one on both.
Perranporth is also excellent, I parked up there overnight, don't recall the exact price but was very reasonable. The town itself is very pleasant and the beach is great, you can walk into town or get a taxi if you have luggage.
Out of the two I’d opt for Perranporth but had a very good experience at both.
If you have the time a trip over to the Scilly Isles is also well worth it.