How do I select transistors for logarithmic amplifier?
Bob Pease addressed this question in one of his inimitable "What's All This ..." articles http://electronicdesign.com/analog/whats-all-logarithmic-stuff-anyhow. See particularly figure 7.

Basically, you set up two transistors to draw the same current, and match for Vbe. 

While you don't say exactly what dynamic range you're looking for, I'd guess that almost any good small-signal transistor will do.