My answer- A Soyuz capsule. Those things have been in service for decades. Unlike successive US space vehicle programs, the Soyuz was never completely replaced, they took the basic design and made successive improvments. Every likely problem, and many unlikely problems, have already occured, and the design has been modified to eliminate those risks. It has an incredible safety record, and there is such a wealth of experience in operating them, that if a critical problem did occur on a flight, ground controllers would be much more likely to come up with a solution than with a completely modern design. Basically, I'd have much more confidence that I'd come back alive on a Soyuz than anything else.
That said, given the opportunity, I'd take a flight on whatever I can get. But if given a choice, I'd choose the Soyuz.