I'm going for Castilian/Japanse/Dutch without the tilde or accent (Ibáñez)
EE-bah-nes
it always cracks me up to hear people say: Eye-banez or Aye-banez, almost as strange as Aye-biza, although in Catalan "Eivissa" for Ibiza is actually correct. But the name Ibiza (like many other spanish names) is in fact derived from Arab.
The surname Ibanez, however, is not of Arab origin, but it could have roots in the Basque language:
http://www.houseofnames.com/xq/asp.c...-coat-arms.htm
Still, all those different versions make it very hard to establish a 'correct' pronounciation.