There's no shortage at all of social networking clients for Android platforms. Seesmic combines a good looking client with flexibility for your accounts and posting options.
This was, it's got to be said, a tough one to choose, and the beauty of that is that you've got lots of choices to make. Twidroyd Legacy has oodles of customising options but isn't being updated. TweetDeck has a sweet UI that's consistent across platforms, but I've been irked by its tendency to crash once too often.
If you just want simplicity and brand awareness, Twitter's own Android app does a pretty decent but plain job. Seesmic edges them out in my estimation, but only just, due to the inclusion of Facebook integration and a neat but clean user interface that concentrates on getting messages through to you. I'm sure plenty of folks will disagree; social networking apps seem to be one of those categories that invites dissent. [Seesmic]