Let's get a bit of discussion going.
To my mind, in T1 every competitive deck has five of its seven dom slots taken out of the gate: SoG, TSC, AotL, CM, and 3W. Obviously there are exceptions, and people make decks without some of these, but even then that's usually for jokier decks and they come back to this core when building seriously.
After this, though, things become more interesting. Some decks have a dom that directly relates into that deck (Holy Spirit, ANB, Glory). Most, though, have two slots left to fill. The most common ones that I've seen are Grapes and Falling Away (either version, though I saw more CoW this year). That said, there are certainly other options - John proved what a terrifying beast Mayhem is this year (although it's a much more challenging card to play/build into a deck), GoYS sees some play especially now that it can block DoU and the like, Shipwreck tends to find at least some value since everyone plays Ends, and if even DoN still sees some play.
So, how do you decide which doms to fill your last slots with? Do you have preferences? If it depends on the deck, how do you decide which to run?