Yeah, those three are pretty much it. They are nice, I guess, but if you just came down from Hotel Dusk you are going to be disappointed.
There are two aspects to playing Japanese DCs if you are gaijin. 1) actually making progress in it, and 2) actually enjoying it.
Games that are easy to make progress in would be Nadia, Gunbuster 1,2, Yuna 1,2, and 3x3 Eyes. These are easy to make progress in because they aren't actually games. You pretty much just click "confirm" for about an hour or two and then they are over. Because of this the enjoyment factor is somewhat low now that the novelty of CD audio with semi-animated cinemas has diminished. You won't have any frustration with not making progress, but you might not enjoy it at all either. Its all a matter of preference.
Games that are harder to make progress in would be Snatcher, or Tokimeki Memorial. In Tokimeki there is an actual game there that consists mainly of just building stats. Once this is explained to you, its actually not very hard to play. I can't really remember Snatcher very well, but I seem to remember there being some gaijin protection on there of some sort. I'm sure someone here knows more than I do about it. Yuna 2 is a straight of DC, but Yuna 1 actually has real battles in it that are card style. They are incredibly easy so you won't have any trouble with them. They just give you something to do instead of hitting the "I" button.
Some Digital Comics are *just* a Digital Comic, and some have bonus stuff in them that IMO adds to the value a lot. For example, the Gunbuster DCs are essential collecting for fans of the anime because they contain new songs, a sound FX player, mecha and character stats. The 2nd one has a comedic "Noriko Battle of the Janken" strip janken game. Its more humorous than pathetic, but just barely...Nadia has a really cool quiz mode, but if you read zero Japanese you'll never pass it. 3x3 is, IIRC, nothing but a story mode.