Originally Posted by Nenkitsune
yep, 16:10 portrait is perfect. at 5x7, the ratio is well, 7:5 hah, which is the same as 14:10. Meaning you'll have a little bit of room to spare on the top and bottom of the screen, which is perfectly fine. Width is more important when it comes to fitting a full page on the screen. I'd rather have a little up and down gaps than side to side.
From ICS onwards, you barely get a top letterbox since the bottom status/nav bar is pretty much spot on for that extra vertical space (unless you're running a custom ROM that allows fullscreen or have an app such as fullscreen+ installed). Completely agree on the letterbox vs pillarbox thing although for me, it also depends on how big the pillarboxes/letterboxes are (e.g. letter-sized PDF has a small pillarbox in 4:3 displays but very large letterboxing on 16:10 when viewed in portrait).