I've got 3 DC's:
DC-3 - Great solo voice, especially with the EV thiele cab underneath it. Lots of gain and sustain. Cleans are chimey, but can get lost with a loud drummer. These amps are way louder than you would think. Mine is Cathode Biased so it gets more sustain and breaks up much easier than it did before.
DC-5 - Good all around amp with lots of volume. More Bass than the DC-3, the cabinet is larger and the 6L6's have more thump. I prefer the DC-3 to it though. My DC-5 had the Mojotone BV-30V speaker in it, which is an improved version of the Vintage 30. Now it is a head, needed the combo cab for my Mark IV.
DC-10 - Much more Metal sounding than the 3. The cleans are thunderous, and the leads are very singing. It is harder to get a Classic Rock tone out of it than the 3 or 5. I have the 2x12 combo with C-90 speakers in it. It's definitely a keeper, but I think I like the Mark IV that I just got the most.
All 3 amps are great, especially for the price. I use the DC-3 at home and the Mark IV for band practice.
The 5 is for sale, and the 10 is my backup for the Mark IV.
DC-3 - Great for Blues & Classic Rock to 80's Metal. I can get some really great SRV tones and Maiden tones out of it.
DC-5 - Great for Classic Rock (didn't dig the Blues tones, but it might have been the speaker) & 80's Metal. These are great all around amps if you add an adjustable Bias pot so you can use different tubes.
DC-10 - Great for just about anything, but I can't seem to get a good Blues tone out of the Lead channel. This is the only amp I have (other than the Mark IV) that has Mesa tubes in it though. I could probably experiment with tubes and find a whole new amp.
It's just my opinion, but these are great amps.