Which ever caliber and size pistol you like the best. If you like .40 in a midsize then the 23 works for you. If it's a full size go with the 22. If you like .357 sig in midsize go with a 32 or say a 10mm in full or subcompact go with a 20 or 29.
It all depends on what you want. What is best in someone else's opinion won't be the best in yours.