Well, last year my wife got me The New Strong's Expanded Exhausted Concordance, Red-Letter Edition (what a mouthful!) This is the one with the Kohlenberger contributions. It also includes the best of Vine's Topical. I've really benefited from this huge concordance. Before this, I was using a small paperback Crudens. And, actually, I never had a problem with Crudens! My wife just decided to buy me the Strong's on my birthday. This thing is simply massive, gargantuan...I get lost in it, really. I do like that the words of Christ are in red and that all the Messianic prophecies are listed. It's really a great book. It even has a list of all the prayers in the Bible, a breakdown of the Jewish feasts, the Jewish calendar, all the Mosaic Law broken down into categories, and a very thorough harmony of the four gospels, with all the illustrations and teachings of Christ.
(edit) The only drawback I see is with the binding. The glue is poor and inadequate for its proportion. I have to gingerly handle the book. The spine has begun to disattach itself from the cover. Otherwise, great tool!
Hope this helps!
Bro. Paul