In my opinion in the long term a verified site i.e. with Meta’s and alts will do better in the search engines so listing only sites like that would be good for you.
I base this on something Matt Cutts said about wishing they could use good coding as a guide to a sites quality but they couldn’t as they kept seeing so many very high quality content sites with poor coding.
Now I am noticing more of these high quality sites being redesigned with verified code (I know I am a geek), a great example of this is
www.bbb.co.uk. The homepage and iplayer pages are new with verified coding but the older radio, sports etc pages are still all 'a mess'. If more and more get designed to standards why wouldn't google and other SE's start using it as a tick in the good box for all sites?