I have owned:
Sig Mosquito
CZ Kadet(pistol not kit)
Ruger 22/45
NAA Minimaster
I think the OP should rephrase the OP so as to make a distinction between revolvers and semi auto's as the revolvers will obviously be more accurate, and reliable.
Of the above the most reliable was obviously the revolver, but thats a given.
Anyways if we are just looking at semi autos, the only one of the above I still have is the Ruger 22/45 as it is the most reliable and accurate of the one I have owned, as well as anything I have ever shot. I bought this thing for $330 brand new and would recommend to anyone. It is about the only gun I can group well with at 25m!
The Sig was reliable for me using Blazer which is cheap anyways so I never had any issues, but it was not very accurate and the barrel would come slightly use after a few hundred rounds. It was also really small, and felt cheap. Not too expencive but more than it was worth IMHO.
The CZ was an amazing pistol and a great trainer as it had the feel and weight of a real gun but the one I got brand new would not lock back reliably no matter what ammo I put through it. The price is ridiculous anyways so kinda made it an easy choice to sell.