Aneros produce the crème de la crème of P-spot massagers. The MGX Classic is firmer and ever so slightly wider than the the company's Helix Syn. Experienced P-spot players love its firmness and the added stimulation that it's ribbed stem applies to the anal canal.
If you're just staring out with prostate play, you might want to check out the softer, silicone coated Aneros Helix Syn, before moving up or alternating your play sessions with the MGX Classic.