Question: Is it allowed to evolve?
I'm tempted to say Scyther, but in real life I'd want a poke that would be able to actually live a long life with me. Scyther is a bug so I'd imagine it'd have a 5 years max lifespan outside of a pokeball. (I know, I'm wierd...I mean seriously, who thinks of this?)
So, in that case - Dragonite.
Also, another question - lets assume one picks a poke and it does die whilst the person is still living, do they get another?