I own 2 (well, 3 if you count the SRD).
I have the Eberron core setting book and Liber Mortis.
I used to own Unearthed Arcana, but I sold it -- pretty much useless to me as I already had all the useful information from it in better forms from free downloads or other books. I had been pressured into the purchase and almost immediately regretted it.
I was already moving towards a more Open D20 feel for my game during 3.0, but with 3.5 I made a wholesale shift. There is very little that has come out from WotC that I have wanted and not found a better version elsewhere.