If you're talking SHMUPs then I have to recommend Ikuraga. Made by the masters at Treasure, it is one of the most unique, challenging, and fun SHMUPs. You can change the "polarity" of your ship from white to black and incoming fire of the same color charges your special weapon while incoming fire of the opposite color destroys your ship. So you have to constantly pay attention to the polarity of your ship, of incoming fire, and of your enemies all while also dodging and shooting. It's good stuff.
I have come to chew bubblegum and kick ass.....and I'm all outta bubblegum.