Well, I have at least 4 24/192 DVD-As (and I only have about a dozen DVD-As), so I'm not sure what you are referring to.
As to which is better, the important thing is that they *both* sound better than plain vanilla CD (HOWEVER, it should be noted that a well-mastered Redbook CD version can actually sound better than a poorly mastered hi-rez version). There are powerful forces behind each format, as well as fanatics (no really, *fanatics*) on either side who will insist one is inherently better than the other. Fanatics will argue that the other format is fundamentally flawed in some way, these arguments can be refuted, and new arguments made. There are people with impeccable technical credentials in the audio arts (gear manufacturers, recording engineers, mastering engineers, artists) on both sides of the fence who will insist one or the other is superior. Bottom line, no two people will agree which is inherently better due purely to its specifications or by listening.
There are differences in the formats however:
1. DVD-A is not a fixed standard. "DVD-A" titles can be 24/48, 24/96 or 24/192, you have no guarantee that each title you buy will be at the maximum resolution DVD-A allows. There is only one flavor of SACD and it's in full-rez all the time.
2. SACD has tons more titles available currently that sell a heck of a lot more than DVD-A. DVD-A however, has tons more machines installed in people's homes (of course most of these people just bought a DVD player and have no idea that it also supports DVD-A, or even that there is a new format called DVD-A).
3. DVD-A currently forces you to attach your player to a monitor so you can visually select which track you want to hear (stereo hi-rez, surround hi-rez, Dolby Digital, etc.). With SACD, it works just like a CD, pop it in and hit play.
4. SACD has hybrid discs available that will play in any CD player, not just SACDPs. These discs contain a standard CD layer as well as a hi-rez stereo and occasionally, hi-rez multi-channel layers as well. These are sold as regular CDs in the regular section for the artist, most people are none the wiser they have a hybrid SACD as they are simply buying a "normal" CD for their collection. DVD-A is coming out with a flip-able version that will have a CD layer on one side and the hi-rez DVD layer on the other. Probably near the end of this year they will start to turn up.