If price is not an issue, go with the 4T. A tower will always outperform a bookshelf. I had to do bookshelf do to WAF. And that is the ONLY reason. I would have loved me some towers. With that said, I do love my 4 5B, 5C and 12D. I am so sure that the 12D is the main reason I don't miss having towers.
Scottiemon