Quick answer no to both.
The Epic a few reasons, one the bathroom layout as Delft said. Shower in one room, toilet in another room and sinck in the cabin, I like to wash my hands as soon as done with the toilet and with this set up the door handle is always going to be dirty, plus the idea of waking up someone else in the cabin with me. Other than that we do not like the way NCL handles the dining rooms. Sure they have lower prices but they really want you to pay for dinner and it shows in the non paying dining rooms.
The Oasis is plan TOOOOOOO BIG.
Now is someone was going to pay for me to sail eith it would the Oasis, it is easier to get over size than all the extra costs.
Star Princess 2005, Sun Princess 2005
Caribbean Princess 2006, MSC Lirica 2006 , NCL Pearl 2007, Majesty of the Seas 2008, Carnival Destiny 2008, MSC Lirica 2009, Carnival Valor 2009,Carnival Legend 2010, Carnival Liberty 2010,Carnival Fantsay 2011,Carnival Valor Feb 2012, MSC Poesia Dec 2012, MSC Poesia April 2013