Hmm, I was writing a bunch of my good moments in a thread on the steam forums a while ago, but I can only seem to remember one. I was on offense on Dustbowl, stage 3, my team had just capped the first point so I made my way into the tunnels and out into the pit below the rocket cap. I bomb jumped up onto the cap, but as I was flying through the air I went directly over a tech 2 or 3 SG with its engie whacking away at it. It tracked me in the air but I was moving too fast for it to keep up, so I fired 3 stickies at it in midair and detonated them when i landed, taking it and the engie out. Didn't manage to get the cap, though =(
Oh! This one is more in the "funny" category, but I was a medic at the last cap of Dustbowl and a heavy on our team apparently got tired of his ridiculously high score, so he just started punching people. I thought this was great, so I healbotted him whenever he respawned. I ubered him around 4 times total while we went in the tunnels to flank the offense. One time he got like 5-6 knockouts, and that time he wasn't even ubered. I remarked after this, "I think we've put the Fear into them".
I have a lot of little "awesome" moments now and then. I like to sticky jump from the train tracks to the spire cap in Badlands, cap it, then run in and nab the last cap (it's worked a few times). The other day I was ripping it up in Dustbowl as a demo; I'd keep sticky jumping into the hallway on the left side with the 1-way door in stage 1 and clearing everything and everyone inside it out. Single-sticky jumping from rampart to rampart in 2fort and bottling snipers is tricky, but always rewarding. Usually I just die horribly to an angry soldier, pyro and sentry, though.
Worst moments... I have lots of those. My k/d ratio is usually 1/1 at the very best, because I'm always the guy who rushes into the fray first, to "lead the charge". Typically doesn't end well. I've ubered an enemy spy who then killed one or two people before feeling my (rather considerable) wrath. I love sticky/rocket jumping (if you couldn't tell), but often an attempt will end poorly when I catch a stray shot before detonating the sticky, resulting in my own "kablooey!". Actually, even though demo is probably my best class, I tend to get a little overzealous when lobbing stickies around, and quite frequently blow my own stupid self up. The list goes on...