Any thoughts on which is better/how these two compare:

Robert Foster's The Complete Guide to Middle-Earth

J.E.A. Tyler's The Complete Tolkien Companion

Descriptions suggest they have similar goals/are trying to be similar things (A to Z list of things).

Tyler's is longer, which is a plus, but Foster's is the one I hear mentioned all the time, which suggests it is the more accepted/appreciated work.

Thoughts?