I believe Tony Miller calls the 3" strops the "New" Standard, because that's becoming far and away the most popular size ordered... but prefers a slightly narrower size for himself. Forgot if I read that on B&B or his website, so I may be completely wrong.
Personally, I have a 3" red latigo. Love the width. Like Lynn says, I wouldn't even dream of ordering a smaller strop, especially since you can use an X-pattern on it anyway. I've got a narrower horsehide - two actually - one with a slight nap, the other with the regular ultra smooth draw. I actually like the one with a bit of nap the best out of the three leathers I've tried. With a bit of use and some strop conditioner (after scratching it up a bit, heh), not only does it give me wonderful feedback, but it's become very quick. Perhaps 90% as quick as my smooth horsehide, whereas I'd say my latigo was 75%. I only wish it were bigger! My preference is for the contoured handles, since my fingers are thin enough to slip between the handle and the strop, allowing me to use it similarly to a D-Ring whenever I like, without having to change hardware.