For example, here are scenes of Luffy from about the same moment from 312:
I don't think I have to spell it out or anything but basically, Inoue rounds out the jaw a lot more and gives the head a rather squarish appearance and straightens out the nose line considerably. Basically, he either rounds out or flattens most of Oda's more subtle angular contours, of course this is usually more obvious in Inoue's female figures.
I suppose there's a bit of bias in that while Inoue's style is a fairly good match for Oda's, I find the particular differences off-putting whereas in Tate's style the slight differences seem aesthetically pleasing to me, conveying a closer feel to the original while perhaps deviating even more from the exact linework.
In any case, my favorites would have to be Tate, Koizumi, and Ide. Ishizuka's alright too, especially in the action department. I also don't really believe that Hisada has been responsible for all the openings since 5. Brand New World looks like Koizumi to me, and Crazy Rainbow Star is different as well. The only ones that seem the same are Jungle P and the newest opening. (which has to be my least favorite style for the anime....)