if there were a new team of three. i would pick either the Spaced stars, Simon Pegg and Nick Frost, their work on Shaun of the Dead was really similar to the Ghostbusters type of humor, and it was flat out hilarious, and they could easily do American accents.
For a sixth member of the team, i'd probably pick Jason Lee, though not a fan of his bad decisions on the late (Alvin, anyone?), i would be certain he can still bring his Mallrats days back.
I think all three would be perfect, since Pegg and Frost have worked together previously, they know how to work off of each other to make it funny, Lee can play a Brodie-type character into the mix (minus the foul language), which would add alot of comic chemestry between all three.
but ofcourse this is my opinion..