[jyl]

Seems to me the most common needs for a knot are:
1. Join two rope ends together
2. Make a loop in the end of a rope (rarely in the middle of a rope)
2. Tie a rope to a fixed object - like a post, D ring, or a loop in another rope

For 1 I usually use a fisherman's knot. I suppose something like a sheet bend would be easy to remember and faster.

For 2 I usually double over the rope then make an overhand knot, for a quick and dirty loop.. (That's also how I make loops in the middle of a rope.) I know I should use a proper bowline (and a proper dropper loop) but can never remember which way the rabbit is supposed to run around the tree. I used to use Perfection loops for fishing, but can't remember them now.

For 3 I usually use a clinch knot. For some reason the standard clove hitch seems insecure to me. If the connection needs to be tensioned I use a truckers hitch.

I learned a few knots for fishing so those tend to be the ones I remember today.