My "best" win wasn't any single fight, but a series of battles leading to my latest and so far most supreme victory in one of the games. This was on a 48-player server.
It started off in the clock tower; I had scavenged iron boots and a diamond from the cornucopia at the beginning, and ran to the clock tower straight after since few people head there first. I had looted both chests and received some leather trousers as well as a wooden axe for a weapon, when I ran into a team of two coming up the stairs; fortunately they were both unarmed, so I manage to chop them down with my axe. They didn't drop anything useful, though.
After this I headed into the brick building on the opposite side of the road to get the chest in the upper floor. Someone else had just entered as well and was exploring the leaf-covered room to the right; he hadn't noticed me, and I managed to take him down from behind while he was trying to fight off a skeleton. He didn't drop a better weapon, but I did get a leather tunic off him. I continued to the upper levels of the building and found another guy near the chest location, fighting a zombie with a stone axe. He didn't notice me at first, and I took him down fighting alongside the zombie (and butchering it afterwards). He had already looted the chest, and I got an upgrade from my wooden axe to a stone one.
I decided to check two more chests in the other brick building next to the clock tower (the one with the elevator) before moving out to raid other players, since I was rather anxious to find a stone sword. Inside, however, I found someone who had looted a conglomeration of chain and golden armor from the cornucopia, but didn't have any kind of weapon equipped; I naturally killed him with ease, and equipped most of his armor. In the chests I actually managed to find a stone sword, after which I was set for a raid.
I started off wandering around all the main streets, but couldn't find anyone. There were still around 20 people left and no one was dying, so I suspected everyone was still looking for chests, teamed up or just hiding. I decided to check on some of the more popular spots people often head to, and started with the big temple thing (I don't know if it's a temple, a bank or a library, but it's the big Parthenon thing with a plaza on two sides of it) and as I entered the building, someone else entered from the opposite side. As a recap, I was wearing chain, gold and iron armor and had a stone sword. He had a stone axe, but stronger armor than mine; iron and gold only. Thus it was fairly even, and I came out as the winner with only one and a half hearts of health left. I took cover behind the bookcases in the middle of the building while I was regenerating health and organizing the armor I had just looted.
At this point I was probably one of the best equipped players still in the game, but I was getting worried about my weapon. Fortunately, I had looted a couple of iron bars from my last fight, and could make an iron sword; I decided against crafting it in the cornucopia though, and used the crafting table on the end of one of the main roads instead. The crafting table in question was next to an entrance to the subway, out of which another guy jumped just as I finished making my sword and attacked me; he had poor equipment though, and I could take him out with ease. Only then did I notice I actually had looted another diamond from my previous fight as well, and could have made a diamond sword instead, which I now did, but my iron had definitely gone to waste in that.
Equipped with a diamond sword, I felt ready for anything, and thought I'd finally pay a visit to the cornucopia. To my great amazement it was actually unoccupied when I arrived, so I camped out there for a bit since the sun was setting and the chests about to be refilled. Once this had happened, I stocked up on my food from the chests and upgraded my armor into fully iron, when someone else with full iron armor but only an iron sword came out of the woods. I pretended to be looking in a chest, he came closer to attack me, and I made quick work of him. At this point there were 10 players left.
I saw no reason for a prolonged stay at the cornucopia and strolled off to hunt down some more players. After a while, I found someone with fairly high quality equipment at the power plant, and had to literally chase him down through half the map, since he was good at running and I was not. Meanwhile a couple more survivors got killed by players unknown, and the player count dropped to 7 after I finally ran down my guy somewhere near the church.
I decided to head into the suburbs, since people always end up there sooner or later. I was fairly surprised to find a poorly equipped team of 3 wandering through them, though. They were walking in a row, and I reached the last of them as they skipped over a bush to head for the river; he tried to fight back with a stone axe, but I just pressed on and killed him in a few hits. The other two were oblivious to what had happened, and I was quickly on the next one since they were only running, not sprinting. He was using a stone sword and had a bit of armor, but was no threat either; the last of them noticed something was going on and attacked me as well, but he only used a stone axe too and died rather easily. All of their equipment was quite useless to me so I just left it on the floor, and the player count was down to 4.
I spent most of this MC day running around the roads trying to look for the last 3 players, but to no avail. Nearing sunset, however, I decided to check the cornucopia once more; and there they were, all three of them. One of them, a sole survivor like me, had apparently looted himself full iron armor and an iron sword from the cornucopia before I arrived and was keeping his distance from the other two, who were a team in partial armor and armed with bows. When they saw me, they dispersed; I decided to chase down the team, but by the time I got where they had disappeared (they were on the opposite side of the cornucopia opening) they were nowhere to be seen. I went back to the cornucopia and noticed the third guy had come back, probably to loot the remaining chests, but ran as he saw me, so I decided to chase him instead. However, due to some awful running and getting stuck in vines on my side, he managed to escape. I returned to the cornucopia just after the refill, looted the chests and crafted me some diamond boots.
At dawn (I spent a lot of time organizing my inventory and checking through the chests) I set out into the suburbs again, which is what I generally do when I'm clueless. I was in luck and managed to spot one of the teamers through a window inside a house at the very end of the suburb; he was trying to hide and probably sneak back to his teammate once I had passed, as they had apparently separated to scavenge the refilled chests. He was covering in a corner with nowhere to run and died.
I went back outside just in time to see his former teammate coming towards me, probably with the intention of helping the one I'd just killed; as he saw me, he turned and ran. I chased him down and cornered him at the wall of one of the ruined highrises next to the cornucopia park; he climbed up a few blocks of vine and started shooting arrows at me. I had a bow as well and wanted to answer the fire, when he suddenly jumped down and began pounding on me with an iron sword. I'd be lying if I said I'd expected that, but reflexes had it he only managed to get one hit on me before I got my diamond sword back out and was slashing at him with it. He died, and it was time for the deathmatch.
My last opponent still had his full iron armor and iron sword, much like the guy I'd killed earlier at the cornucopia. His only chance would've been to come at me right away, since I was actually down to 3 hearts from my last battle; but he was too careful for that, and I got the opportunity to regenerate with 3 golden apples. After that, the fight was a mere formality; I just ran straight at him and dealt out blows till he was dead.
Which brought my total kill count for that game to 15.