The DCCC has sent out a fundraising pitch I made for them. You can read it there.
I encourage people to give to a variety of candidates and organizations, there's no "right place" to give. But, as I explain in the pitch (hopefully well enough), the DCC C is in a position to really do what no other organization can at this point in the election cycle, given campaign finance laws and their institutional mandate. They're the real strategic players in this game, figuring out where and when to drop money and support into races. House races can change quickly, if a mini-scandal bubbles up or an attack ad manages to have impact. Every candidate's fundraising and media buys are basically public knowledge, but the DCCC gets to make the surprise attacks (and respond to surprise attacks from the other side), dropping an extra few hundred grand into a race at a critical moment.
And, for people who hate spam - it was their email list, I have nothing to do with it. If I didn't make the pitch, then someone else would have...