Dont get the O.S. 30vg. It has ABN construction instead of the ABC construction. They wont last as long and i hear they arent all that powerful.
An LRP .28, or .30 or Picco .28 are an excellent choice and will be awesome power. They are a little expensive and you need your drivetrain to be in pretty good shape to hold up to it.
I am running an Axial .28 spec 1s. Its been great for me, but some say they have bearing and carburetor issues. A couple of other good motors are the Sportwerks .26(hard to find), and a Mach 427 which can be had pretty cheap and will be a nice power increase for not a whole lot of money
Hope this helps!
Eric