Spec V by far, it runs low 15s, thats just as fast as a lude, up to the 1/4 mile that is
2003 civic si, AFAIK runs high 15s.
Now modification wise, as you know there is a HUGE aftermarket for Civics, can't say the same for Spec Vs. So if you are into hardcore modding, you can probably make your SI much faster.
Choice is up to you.