P3-24 if you're going with those two only. Secondhand might get you a Roksan Radius for the same money though and this is well worth considering.
For the P3, think about a Dynavector 10x5 cartridge (£250) which is a stunning match apparently, by all accounts, also - depending on the sound you like - the Audio Technica AT440-MLa (£90) which is open, detailed and tracks like a winner. It's easily worth half as much again, so this is a bit of a steal. If you buy in the US, you'll get it for about £60 or so and for that money, it's a giveaway.
Don't forget the Goldring 1022/1042 and new Ortofon ranges as well (2000 series variants). All will do a good job, but check out the tonal qualities of each viz what you want to hear. I'm utterly delighted with the AT, but would only recommend it if you like an analytical, but highly open and musical presentation. If you want warmth, look elsewhere.