In The Know Today Theme! I've been using it for about a year and still love it. I've switched to others but always come back instantly. If I were to create the perfect theme, it would be this one.
There are many really good themes, but my favorite (in addition to the one listed above) is called 7plus by BerriMobi. I have a Storm2 and absolutely LOVE this theme and, once installed, I haven't gone to any other. It is extremely functional, great details, and no problems with battery drain or bricking. Works smoothly even under stress - when lots of things are going on. Highly recommended. Clean home screen, too. Lots of room for wallpaper and customizing. Uses hidden today and QuickLaunch by touch. Here's the link (very hard to find in the App Store unless you know the specific name; there are lots of Windows 7-based themes)...
I've been using Reverie Theme on my Tour for the last 6-7 months and really like it, though I'm thinking about trying out Wall-E when I get my Bold 9650.
Unfortunately you can't get this one anymore, RIM had it pulled But I LOVE WJD's OS6 Theme! I still have a legacy copy, but you guys can;t buy it anymore thanks to the RIM suits.
For my new Bold 9650 which replaced my Tour 9360, I purchased the Appleberry Theme Suite:
Works great for me and I love it!!!
Basically, I will keep it at least until I go to a new device model....who knows when that will be......
Also worth mentioning.....Andrew Hastings, the developer, has been great with customer support so far. Not that folks need too much when it comes to themes.....