I've thought of an easier way out of this question Liam;
My most important piece of equipemnt is....my fishing vest! Without it, I wouldn't be able to carry all my floatant, sinkant, tools, gadgets, unguents, leader spools, tippets, flies, snips, forceps, fags, lighter, cameraphone, net, brown polaroids, yellow polaroids...etc etc
Ewan