There is absolutely nothing "definitive" about my list given below except that it happens to comprise the set that I have singled out as my personal favourites, among hundreds of recordings that I've picked up over the years. I can't now remember why I selected any of them, except that they're all based on a good comparative listen. I daresay that if I were to go through the whole lot yet again I might come up with a different list.
Of those pianists mentioned by others, I would say that I don't much care for Glenn Gould's Mozart. I don't like the guy's playing except for Bach, and even then I prefer others'. Argerich is not much good for Mozart. Horowitz ditto. One of my overall favourite pianists is Maria JoĂŁo Pires, and I'd buy more of her Mozart piano concerto CDs if I were in the market for yet more of Mozart, but I'm not. Perahia is another favourite, as to is Mitsuko Uchida and Ingrid Haebler. I also like both Ashkenazy and Barenboim, and either of their sets (of the later concertos) would be a good starting point.
1 K 037 - No 1, Ashkenazy
2 K 039 - No 2, Barenboim
3 K 040 - No 3, Anda
4 K 041 - No 4, Perahia
5 K 175 - No 5, Uchida
6 K 238 - No 6, Greilsammer
7 K 242 - Concerto for 3 pianos in F major, Lodron, Ashkenazy, Barenboim, Fou Ts'ong 8
8 K 246 - No 8, LĂĽtzow, Kocsis
9 K 271 - No 9, "Jeunehomme", Kraus
10 K 365 - Concerto for 2 pianos and orchestra, Elena & Emil Gilels
11 K 413 - No 11, Haebler
12 K 414 - No 12, Pires
13 K 415 - No 13, Jando
14 K 449 - No 14, "1st Ployer", Moravec
15 K 450 - No 15, Kempff
16 K 451 - No 16, Schiff
17 K 453 - No 17, "2nd Ployer", Pires,
18 K 456 - No 18, "Paradies", Goode
19 K 459 - No 19, Pollini
20 K 466 - No 20, Ashkenazy
21 K 467 - No 21, Ashkenazy
22 K 482 - No 22, Richter
23 K 488 - No 23, Pollini
24 K 491 - No 24, Ashkenazy
25 K 503 - No 25, Serkin
26 K 537 - No 26, "Coronation", Uchida
27 K 595 - No 27, Uchida