Close one, they're both great. I'd say HT is the more consistent, but Meteora's great songs are better than HT's, if you know what I mean? As in, P.O.A, One Step Closer, In the End < Numb, Faint, Lying From You. I'd say, for that reason alone, my favourite is Meteora. Favourite song changes often, but it'd be between Faint, Numb, Lying From You or In the End.
ATS is nearly as good as both in my opinion btw :) Waiting For the End is awesome!
Meteora was my first Linkin Park album and the one that got me hooked on their music. I was so sure at the time that they would never release new material and I was proved wrong when Minutes to Midnight and A Thousand Suns came out!
I got Hybrid Theory as soon as I had listened to Meteora a hundred times, but I'll always prefer Meteora! It has a hook that I can never find the words to describe.