I have personally avoided running plugins when manual code could provide similar functionality. But Digg Digg made me change my mind in one particular case and I replaced manually placed codes with their WordPress plugin on this blog.
Digg Digg looks nice. Has all the necessary features. And best of all it does not push their own branding through their share bar that you see on the left of this blog post.
They do add their link in the share bar but you have the option to disable it.
They offer buttons for all the popular social networks and regular updates would ensure that the code is optimized and new networks would be made available.
If you are looking for a sharing plugin for your WordPress blog, I would suggest giving Digg Digg a look!