I prefer omnibuses over absolutes. Here is my list:
1. Swamp Thing by Alan Moore
2. Batman by Jeph Loeb and Tim Sale (including The Long Halloween, Dark Victory, Haunted Knight and maybe Catwoman When in Rome)
3. Batman by Grant Morrison (I'm not sure how many omnibuses would be needed...)
4. Promethea
5. Top Ten (including the issues that weren't collected in the absolute)
6. Seven Soldiers of Victory by Grant Morrison
8. Ex Machina
9. Starman
10. Batman by Scott Snyder and Greg Capullo