My top 6 DT albums (the real heavyweights) are evenly split between the first and second half of their career, so it's hard to decide for me.
1. I&W - 1st half
2. TOT - 2nd half
3. ADTOE - 2nd half
4. SFAM - 1st half
5. 8VM - 2nd half
6. Awake - 1st half
If I go further down the list though, 3 of my bottom 4 DT albums are the remaining three from the 1st half. So I guess 2nd half comes out on top looking at things as a whole - but I struggle to vote against a group that has I&W in it when it's a close decision!