As of this very moment, if I could only keep one handgun, it would be my CZ PCR - which is very similar to the newer CZ P-01 and is a 9mm. Great ergonomics, reasonably light, decent capacity at 14+1, outstanding trigger for a DA/SA with no trigger job. I've only put 300 rounds through mine but they have been 100% reliable and it is currently my daily carry.
I also have the utmost respect for my Taurus PT99. Many, many flawless shots fired and no problems at all. Trigger could be better and the grip isn't the most comfortable, but I'd be glad to take it into a combat role if needed.
Other various CZs, EAAs, SIGs, a Beretta, a Kahr have been trouble free as well but if I could only have one for all purposes, it would be a CZ PCR or P-01. For a dedicated range gun, I'd probably go for one of the all steel CZs.