what active band are you hoping and waiting the most for their next release? It could be a band that hasn't put out a cd in a while or one that just put out a cd. You can list more then one band if you can't narrow it all the way down.
When a band I like puts out a new album I'm typically giddy for about two weeks; wearing the album out. Then I go through a period of legitimate depression knowing I won't hear anything new from them in likely a couple of years.
Arkells
The Horrible Crows
Fake Problems
The Hold Steady