I recommend the Rega Exact because it's a good all around performer that is made to match up well with Rega tables and arms. I have a Rega RP10 and Rega Apheta 2 MC cartridge and the match is excellent. IMO, when you go with a non-Rega cartridge it's a hit or miss proposition. If you buy a non-Rega arm, you may have to shim it to get it to the proper height.
I have 2 turntables, the Rega RP10 that comes with the RB2000 arm and a fully upgraded Linn LP12 with the Ekos SE arm. I went with the Apheta 2 for the Rega and a Linn Akiva for the LP12 and I'm very happy with both of them. The engineers at Rega and Linn design their cartridges for their tables and arms so you know you're getting a good match. I'm not saying that the Exact is the best because that is a very subjective term but you could spend more and get a lot less.