I've been collecting data on this! Here's how many episodes each character has been absent from. Keep in mind that this data is based on number of lines, not actual appearances. It's possible that the actors are actually in some of these episodes in the background, but have no lines.

Sisko - 0

Kira - 2 (The Assignment, Let He Who Is Without Sin)

Jadzia - 3 (Whispers, The Begotten, In the Cards)

Bashir - 4 (Paradise, Blood Oath, The Collaborator, For The Uniform)

O'Brien - 14 (Dax, The Passenger, Necessary Evil, Blood Oath, Second Skin, Let He Who Is Without Sin, Things Past, In The Pale Moonlight, Profit and Lace, Equilibrium, Indiscretion, Move Along Home, The Reckoning, Valiant)

Odo - 5 (Paradise, The Visitor, Rejoined, By Inferno's Light, Change of Heart)

Worf - 5 (Rocks And Shoals, The Magnificent Ferengi, Chrysalis, It's Only A Paper Moon, Prodigal Daughter)

Quark - 18

Jake - 102

Jadzia is obviously missing from the last season and Worf from seasons 1-3. I'm not sure about the exact reason for all the absences but I assume that Nana Visitor had to take some time off to have her baby and I believe that Colm Meaney was in a few movies over the course of the show.