~~I don't know about the versions, but I believe~~ there is one with an introduction by Enda Duffy. Get that one, if you can. He is an incredible Joyce scholar and happened to be my favorite professor during Undergrad.
this is the version you want! http://www.amazon.com/Ulysses-James-Joyce/dp/0486474704/ref=sr_1_1?ie=UTF8&qid=1419965743&sr=8-1&keywords=ulysses+duffy
When you read Ulysses, don't, for god's sake DON"T read for plot. You will become so frustrated. Read instead for the beauty of the words, the way he uses language, makes it stretch, battles it into a new form. He's not as much into syntax, but the WORDS are brilliant. Try reading parts of it out loud. Think on the themes of why Joyce chose to write this story, and why he wrote it like this- Irish-English tensions, personal experiences in school, the entire Modernist movement. And as you read through and enjoy how the words dance, how the messages- oh the messages- are constantly changing and reacting as bloom interacts... man. Its a treat! And the plot, the story, it does come alive. But if you read it for plot, you will miss it.