I thought they started off VERY strong, but some of the later games weren't as amazing as the early ones.
I would rank them...(and yeah, I put DeathSmiles above Ketusi and DOJ...this is personal preference, not exactly what's the "best")
EDIT: This will alter, time to time (as if anyone cares), because I took a big hiatus from shmupping, and am now playing these more regularly.
Also, I will toss in some info, just to make the list more interesting.
God Tier:
ESPGaluda II - This is one of my peak faves, from CAVE. People tend to give it grief, for being too hard...but whatever. It's just epic, and has amazing designs and gameplay. I would put this in CAVE's top 3 games, all together.
Mushihimesama Futari 1.5 - Everyone knows this one is great. Just put together amazingly well.
Guwange - This game has flaws. But the art kind of makes up for it.
Deity Tier:
DeathSmiles MBL - I love this game. I know the hardcore aren't that into it, but I just think it's a blast. And once again, Jun's designs are phenomenal. Also, it's a hori, but actually plays like one. Unlike most of CAVE's horis.
Ketsui - Great game. Duh. Nothing too "special" about it, other than being a great game. The port is good, but it's a little laggy. It's more responsive in MAME.
Do DonPachi Dai-Ou-Jou BL - I don't like it as much as DDP, but it's still really strong. I have problems with it, but it certainly will separate the men form the boys...or the obsessed from the sane. This port was improved, by the patch. But the load times are still poor, until you get the game going.
Demigod Tier:
Mushihimesama HD - I've ALWAYS thought this game was over-rated. It's a good game, but it doesn't rock my world. It is beautiful (which I can see now. the PS2 version always clouded that), and has amazing atmosphere. Also, it has two classic stages (3 and 4), which are really something.
Akai Katana Shin (for the Shin/Slash version) - Returning to this game, it's definitely better than I remember. The Shin version, is the only version. I think they kind of made this game good, with the home port. Adding an extra stage (which is a good one too), and coming up with much better controls, was really great. Also, it's the only manly game CAVE have made, since Ketsui. I mean, the guys look fey, but it'll pass. I would have loved a sequel to this. They could have really made a great game with the foundation laid here. I'll give them props for coming up with a pretty odd system, that works.
Muchi Muchi Pork! - Goofy and solid game. There isn't really much to say about it. Do you like fat girls?!
Do DonPachi: DaiFukkatsu Black Label - Black Label is the only version I can get into, thus far. I find the artwork to be a bit uninspired, but still solid. The bosses look awful. I'm not sure about it's difficulty yet. This was during their "let's get new players" phase, so it's not as hard as usual. I still have to figure out how easy it is. Over time, I may like this more than MMP. I'm sure some people think I'm insane for liking it less than MMP.
After that, there's Pink Sweets. Which I can't really see the appeal of. It's like a goofy Ibara, and it's missing all the cool stuff Ibara had. This is one of the few Cave games that I have almost no interest in at all.
I think all I am missing is the last Do DonPachi. Which seemed really blue. AND DeathSmiles II, which I will not play, unless someone just tosses it in front of me.
How would you rank 'em? Even though CAVE is dead, this was kind of a massive explosion of quality shmups, on this system. I have fond memories.
I don't think we're going to see something like that again.
