Gentle Alarm, I'd say. It's a paid app but there are tons of ways to customize it. My favorite feature is the fade-in alarm and the fact that you can set "night display" - I use that as my clock overnight.
I use Kaloer Clock and have not had any issues with it, and a nice little feature of it is that it will start the clock screen when it is charging automatically (like my Storm 1 did).
I got both Gentle Alarm & Alarm Clock Xtreme when they were Amazon Free Apps a couple months ago & I prefer Gentle Alarm over all the others I have tried. There is no limit to possible customizations.