I was going to check out Alkido based on the comments here, but even some of the positive reviews on the market said it ran slow. I suspect it's another of those apps that's great if your phone is fairly current, not so great if it's an older model. (Angry Birds and Handcent fall into this category for me, if that gives you an idea.) Moon+ has full font customization, everything from font size to line spacing. It's a fairly small program, books tend to load kind of slow, but the app itself is fast. Smooth scrolling to read, which I prefer to page-turning (though, I'm pretty sure that's an option if I did want it), decent organization system. Another big plus is that the free version's ads are only on the bookshelf, so it doesn't interfere with reading. I admit that it's the only one I've tried other than nook for Android, but that one was so slow that I could set my phone down, go make a sammich, and come back to find it still trying to load a book. It actually put me off readers entirely, because it made me think maybe my phone's just not capable of running one decently. Having found one that runs so smoothly on my phone and does what I need it to, I haven't even bothered looking at others.