The thing about an expository dictionary is that it makes no apologies for the fact that the theological bias of the writer will be evident. Vine came from a Christian Brethren background and his convictions will show in his dictionary. The same is true of Renn and Mounce who are more Reformed in their thinking. Vine's has the Old and New Testament sections separately while both Renn and Mounce combine Old and New in each item. There is, in my view, and advantage to having both Hebrew and Greek words on the same page and place. My personal preference for the 'expository' side of things would be Vine. I think his views are closer to mine and I think he does a very good job of providing a Biblical Theology to undergird your studies. Renn's comments are the most full.
However there is a gem in Mounce.
He has a section on "How to do word studies" which I cannot recommend too highly. In fact you can read this whole section on Amazon without having to buy the book at all. This is the way I have done 'word studies' personally for many years and have encouraged others to study in the same way. To see it expressed in this way is a great encouragement personally and he adds some follies of interpretation to be avoided. This is a mini-course in hermeneutics and a priceless help for students of the Scripture. If these guides and cautions were carefully observed we would prevent many presumptions that have littered Bible teaching for many years.Do read it and think through the implications.
So which is the best? For me the claims of 'better than Vine's' are not substantiated but both Renn and Mounce add some valuable content.
Check out the options:
Vine's
Mounce also has a Kindle version
Renn
