One negative to Songbird is the MediaFlow plugin.
I always seem to have to refresh the artwork because the library can't 'find' or 'doesn't have' the album art on the display.

I really like songbird. Especially the monitor watch where I can monitor a specific folder for a playlist. All songbird is missing a minimize tray (like itunes and wmp), and the display title on the taskbar (like winamp).

WMP and iTunes and foobar uses a criteria, but none of those have "folder watch".

There is an add-on for minimizing to the tray, I'll go dig it up once I get home lol

EDIT: Aww shucks, not compatible with 1.1.1 yet. :(

Here are the extensions and feathers I use:
ACM MP3 Decoder
FocusTrack
Glossy Coat2 (feather)
iPod Device Support
Last.fm
LiveTweeter
MediaFlow
MinimizeToTray revived
MTP Device Support
Pane Buttons
Pause/Play/Stop Buttons
SHOUTcast Radio
Vinyl Album Art
Windows Media Playback

Obviously some of these came with Songbird, and some of them also haven't been updated for 1.1.1 yet. :(