I bought the Ulysses (Gabler Edition) edition of this book recently as we were reading Ulysses as part of an online book club. The advantage of that edition is that it is popular edition and also has line numberings so that as part of a group you can immediately locate a piece of text.
Joyce edited and added bits and pieces to the text over the years much to the chagrin and frustration of his publishers, so you can expect minor variations between editions, yet they may be 95-99% similar.
"Ineluctable modality of the visible."
There are certain passages that no dictionary will help you with, and that is why you may need a companion book, such as Ulysses annotated, which explains the many allusions, whether to Latin, parallels with the Bible, with the Odyssey which this story loosely parallels, to Latin, British Rule, historical context, local maps, Hamlet, mythical search for the missing father, Shakespeare and the Bible.
The further you get into this book the better it gets.
At once this book is inpiring yet challenging, sometimes perplexing yet ultimately rewarding. Full of inventive wordplay that sometimes defies instant comprehension. I have read entire pages that turn out to be word salad at first. Every chapter has a different narrative style, such as inner monologue, narcissistic, catechism, stream of consciousness. Sometimes this book is brutal to read, sometimes a joy. I can understand why this book is so influential, and the words nibble at the edge of your consciousness forcing your mind to expand itself. This book has changed the way I think about writing, as I have never seen som many different narrative devices used in a single book before. The final chapter with Molly Bloom in bed, with its runon sentences is simply hilarious.
And if you search you can find free online chapter summaries of chapters to speed your comprehension.
I hope you found this review helpful.