Personally I would look at a rack / multi effects unit - foot switchable.
A short delay on an acoustic with no feed back always sounds good to me
A reverb where you have the ability to not have the reverb tails, i..e just the reflections is cool.
Modulation is right for some songs
Compression can be good as well.
I do like what I have heard of the TC Electronics pedals online, but do not gig myself so have no real need for them. But if you like things like delay / verb / comp all at the same time then having multiple pedals means a bit of tap dancing rather than swicthing to one patch.
The TC G Natural would seem the obvious choice if you want a multi effect pedal though - not that cheap £600ish.