Well, generally we can't really help much unless we see what kind of movesets you were interested in and go from there.
Either way, personally, for the eeveelution, you're probably better off going with something that can support your team since you're undecided - either Umbreon or Espeon could do this (wish/STAB and two others - Calm Mind Espeon and depends for Umbreon). But! Vaporeon, on the other hand, can really help you with water absorb, though only one of your Pokemon are weak to water, so it isn't that much of an issue -- however two are weak to ground, so it COULD be helpful. Flareon generally sucks, and Jolteon is pretty good with its speed, so it's really up to you.
Personally, I think Pidgeot can be a lot more useful, it's faster, can abuse Return better than Noctowl and generally is good throughout the game. :x
As for another Pokemon, I think it's best to see what you'd like to give the others and check your weaknesses, using another Pokemon to cover them.