Personally I use TwitHawk. Works great for me, has an automatic feature, and since I'm not always on the same PC the fact that it's a web app really comes in handy. But that's just me.
If you use tweetdeck for lets say 30 accounts , twitter only lets you have 5 accounts per household... so doesnt tweetdeck just give twitter all the info they need on how many accounts you have and then they could just suspend your accounts ???? #ValidQuestion
For my point of view the tweepi is the best software for me. It is very easy to use. Also manageflitter is the good tool for twitter.