Which Concordance

I'm going to take advantage of the recent lull on this list to ask a
non-technical question.

I'd like to use my upcoming tax refund to get a good NT Greek concordance
and so would solicit any advice, suggestions, comment, etc. that any here
might have as to which concordance that I want.

The following are listed in my current CBD catalogue:

  - Concordance to Nestle-Aland 26/UNS 3, deGruyter.

  - Clapp, Friberg and Friberg, Analytical Concordance to Greek NT, Lexical

  - [ditto] ... Grammatical Focus.

(BTW What exactly is the function/meaning of the "Lexical" vs "Grammatical"

Any others I should be thinking about?


P.S. Speaking of concordances and CBD, if anyone's interested they are
currently offering the Exhaustive Concordance to the NRSV for $9.95[!] as a
close-out. --N