UE3 would make more subs no doubt, Tera is a good example not because of the art style but the technology behind it.
For example Tera is scalable it has tons of graphical options that can make the game run on a toaster at full speed like WOW, something Bioware didnt understood. For a MMO to have the broadest market penetration the engine needs to be scalable meaning running ugly but highly playable at lowend systems and "better" at highend ones. Tera does it, WOW does it and GW2 does it aswell. Swtor at launch and still doesnt do it good a mid range system looking for more FPS can put all the low amount of settings at lower and still may not gain even 1 FPS.
Bioware aquired Hero engine licence for its WYSIWYG content production but then even them said there was problems with it, then post launch and with the sea of criticism Hero engine CEO came "washing his hands" saying what Bioware using of Hero engine isn't even most of they code.
Growing pains from hero engine as Shown in this article from 2009 where SWTOR developing was in full swing
http://www.gamasutra.com/php-bin/new...hp?story=25316
Even Bethesda that had a licence of Hero Engine decided to make a inhouse custom engine for his Elder Scrolls Online instead of using the licence of Hero Engine they had purchase.
This says it all:
http://www.gameinformer.com/b/featur...eroengine.aspx
They used the engine to quick make a prototype and thats where the engine is good in creating fast content but decided that the engine isnt good for massive deployment