My best day ever was a couple of years ago when my then 8 year old son and I went to a local lake. He had just about given up on bass fishing for good because he'd yet to hook one after multiple trips... lots of bluegill and crappie and catfish, but never a bigmouth bass. But somehow, on that day, every single fish in the lake suddenly "turned on" and he caught 18 nice-sized fish in a row, literally on every other cast. The funny thing was, I only caught a couple because I was so busy helping him land and unhook the fish he was catching. To this day, he still talks about the day he out-fished daddy 9-to-1, and now he's my best fishing partner. ANY day out with him is special.
Another one was when he and I were offshore and I told him if he caught a fish over six feet I would mount it for him, knowing that we weren't in "big fish" water at the time. BUT, somehow he managed to hook into a 6 1/2 foot shark. He fought it for 45 minutes and finally got it close enough to the boat that I could get a gaff into it and haul it aboard. He was 10 at the time and henlanded it all by himself... wouldn't even let me help him reel when his arms started hurting. The smile on his face was incredible, and now he has a big toothy shark mounted over his bed.
As for me fishing solo, the best day was 2 summers ago when I was fishing in the upper Potomac. I was wading in a quiet section of the river, and I was catching nice smallies on every cast, it seemed. But to make it even more amazing, while I was retying my line, a huge bald eagle suddenly swooped down and snatched a fish out of the water literally 20 feet from me. It was the single most amazing "nature overwhelms me sometimes" moment of my outdoor life. In 40 years of hunting and fishing, that moment still stands out to me... Our national symbol is a truly, truly awe-inspiring creature.
Funny, but my 40-bass days don't really stand out in my memories, but the experiences above are going to be with me until the day I die.