I have the Samsung Galaxy S2 at the moment...Looking to go over to Verizon and either get the Samsung Galaxy S3 or the Samsung Galaxy Note 2....with that said, I also use Handcent SMS Pro
Titanium Back up-I rooted my first Droid..
I use the Flashlight app
Foxfi-it allows you to use your phone as a hotspot, so if you want to get on the web with your ipad or some other WiFi device, you can..
Go Launcher Pro- instead of the Stock Home Launcher. You can add more screens and even have 3 customize-able app drawer on the bottom as well.
I'll add more later...but these are just a few of what I like to use..
Handcent is a must have for me. Best messenger replacement out there. Also the rom I use has wifi tethering built in, so no need for an extra app for that. And when you upgrade to a Jelly Bean phone check out Nova Launcher. It is beautiful.