Once again a poll tries to keyhole divers, and it just doesn't work/fit.
For example, when diving just for fun in warm clear waters, the Lovely Young Kat, my Bride, is my main buddy, but sometimes it's either or both my daughters. Unless, of course, they've all gone shopping, when my "cold water/high current/low vis/lousy conditions" buddy & I ('cause *his* bride will be with 'em too) will dive together. My "lousy conditions" buddy is another old fart who, like me, is willing to dive in a mud puddle in the wintertime just to get wet. He's also my wreck buddy.
My caving buddies are cave nuts who I have to blast out of the springs to get them to make the occasional salt water dive...
My instructing buddies are my DiveCons (Dive Control Specialists - SSI version of Divemaster/Assistant Instructor).
There are also my "occasional" buddies - my old college roommate, for example, who lives 8,000 miles from here - we'll meet somewhere to go diving every couple years or so.
My main spearfishing buddy is my brother-in-law.
Rick