Well, Jak 2 does look very impressive...but there are plenty of games that stand above it.
Out of those Cube titles you listed, I found
-MP
-Starfox Adventures
...to be somewhat more impressive. SFA is kind of neck and neck, though. SFA has better textures, better models, and more effects in place...but the worlds are much MUCH smaller in scale and there is a lot less going on. The problem with Jak 2 is that the framerate isn't constant. It holds 60 fps in a lot of mission areas, but the game has issues in the city at times. Nothing horrible, but it feels less polished as a result.
I'm not a fan of Jak's art design, but the world is very impressive to behold. Each character in the city is fairly detailed and, although many look alike, there are a TON of them wandering around. The city itself is also quite geometrically dense and large in scope.
The overall visual package, as you say, just isn't that hot. It shines in many areas, but falls short in others. Jak 3 looks a bit more impressive to me (though still very similar) and Ratchet and Clank 2 certainly looks more attractive thanks to a much more consistant framerate.
It most certainly stands up to a lot of the best looking Cube games, but it doesn't exceed them at all. The PS2 isn't even capable of displaying some of the effects you might find in those Cube titles, so that's another issue you have to consider. I wouldn't even consider comparing it to all of those Cube titles listed either. I mean, F-Zero? Come on, that's so different looking. F-Zero is actually rather simplistic looking in a lot of ways, though. Take a look around sometime and you can see just how low-detail most of the environments really are (especially those forest rings).
Really, though, Metroid Prime stands among the most polished games this gen so it's hard to compare anything to it. Everything about it just screams perfection.
I have not seen much of FFCC, to tell you the truth, but I am not suprised that it beats out all of the PS2 FF games. None of them have been technically impressive IMO. I mean, even for the time, FFX had a lot of major problems right out of the gate. There are other, better looking RPGs on PS2 though...just not FF games.
Starfox I have never seen in person... does it run at 60FPS?
Mostly, yes. It also has some screen tearing and slowdown, though not nearly as often as Jak 2. The actual world geometry is fairly simple most of the time, though, but it has very high-res textures and lots of cool effects (the grass and fur effects look excellent, for example). It also has a streaming world, but I recall there being really nasty pauses and skips while moving through a loading point.
I am playing Billy Hatcher and I am surprised. It has some of the nicest water I have ever seen.
It has some nice water and a few cool effects (like the snow), but that's it. Jak 2 murders Billy Hatcher from a technical POV. Jak 2 probably pushes several times as much geometry as BH and is generally much more impressive overall. BH also has a lot of slowdown just like Jak 2...but in this case, it isn't justified. Jak 2 will slowdown when there is like 30+ detailed characters plus a massive city backdrop on the screen...while BH will start sputtering at almost random points. It's a colorful, solid looking game, though...but it can't even begin to compare to even Jak and Daxter let alone Jak 2 or 3. Oh, it also doesn't even try for a LOD approach. It literally just removes all objects from the world until you get near them. Fences, rocks, boxes, and all other detailed objects just aren't present until you reach a certain point...so much of the distant world is just made of flat surfaces.
Here's what the early city section look like... (ignore the high resolution, though).
The textures are probably the largest flaw, though they look much better in many other segments (and really, the high-res shot reveals more about them than it should). You can clearly see just how much detail is put into the environments, though. That is consistant as well (the worlds are generally as detailed, if not more so when the camera is showing more of the world).
Star Fox Adventures...
Bleh, it's very hard to find good SFA images that show off the world somewhat. These are two of the best area shots I could find and represent what the world looks like. As you can see, it isn't constructed out of nearly as much geometry, but the textures are much higher in resolution and there are more effects/features present.
Jak 1
Even MORE difficult to find good shots for. J&D is the only game being mentioned here that doesn't support progressive scan and, in fact, only runs with a half frame buffer. Still, it is VERY colorful (on an actual TV, not in the shots), runs at a perfect 60 fps, and has a great draw distance. You can see that it has aged quite a bit, of course, but it still looks nice enough.
Billy Hatcher
Once again, too many "zoomed in" shots out there. It's hard to find shots that attempt to show more of the world (while remaining in game). The flaws I mentioned are obvious here. The background detail is very low (low geometry and mediocre textures) and the game has slowdown issues. It looks much cleaner on my TV, though, running in 480p. Very bright and colorful (though you wouldn't know it from these shots).
