BLADE - Slick and attractive. Good photography. Articles are decently written. Covers most areas with a lot on custom/handmade and art knives.
KNIVES ILLUSTRATED - Not quite as slick as Blade and more general in coverage. Decent photos and articles. .
TACTICAL KNIVES - Not quite as attractive as BLADE or KI. Usually a good number of photos, but many in b&w (not that there is anything wrong with that). Emphasis is on tactical fixed blades, though other things show up. Reviews are frequently quite extensive.
KNIFE WORLD - A newspaper style "magazine". Emphasis is on traditionals...usually older factory traditionals, collecting, and historical information. While not flashy, the articles are very well written with a wealth of historical information.