It's difficult for me to single out a moment because I've had so many different experiences over the years. I remember having some amazingly close and clean FOX/MRT/UF1 battles, driving through the night until the morning with some great drivers and trying to survive the carnage of some of the crazier pub servers.
If I had to pick a single race I'd probably go for a 40 lap BF1 race at Aston GP Rev that was part of the DSR Road 2 F1 series in 2009. The race was memorable for a number of reasons (including me misjudging a lapping attempt and accidentally smashing a teammate up the rear), but the last 10 laps were what really made it. Storm Cloud (who was and still should be recognised as one of the finest open wheel drivers in LFS history) was also in the race and he'd been in a few scrapes himself throughout the race. He pitted for the last time at the end of lap 30 and exited the pits in 3rd place. I was about 5 seconds ahead in 2nd place and another teammate was in the lead a further 7 seconds ahead of me. Over the next 10 laps I drove harder than I think I've ever driven in any LFS event, trying to keep Storm behind me and chase down my teammate to take the win. I should mention that Storm had a significant amount of suspension damage, so that definitely slowed him down, but I didn't know that at the time. I was just going balls to the wall. As I said in chat after the race it was like a nightmare where someone's chasing you down an alley and you can't do anything to hold them back. Here is the race replay. Skip to about 1:07:30 to see Storm approaching the pitlane for his last stop.
This is a surprise to me too, but between the a whole season of STCC and the 24h MoE race with 3id the title of most memorable experience in LFS has got to go to the Road Sport Summer Cup. Seriously, 3 seasons of awesomeness.
Favorite for me in my short-ish time in LFS is the 24 Hour race this year. I stayed up for 38 hours that day...and night...and following day, drove 3 stints from 2AM-4AM and again from 5Am till 6AM. The team got its best ever Endurance finish (14th overall) and a podium (3rd in Am class). It was just the culmination of 7 years of work: of starting a team between some buddies in a different game in a small league. Coming to LFS, entering broadcast races (that just blew my mind), running for 24 hours, and at the end being one of the 6 cars called to the line for the podium photos. We were lucky to have come really cool guest drivers who were willing to work with us.
The moment I like to remember most was the UFRC May-Hem Cup Season 1 Division 2 UF1 race at SO1, where I won starting from pole after reversed grid, defending the position throughout the race against Dru of Zwarthe Wind Racing back in the time.
The following season I finished 3rd in the UFRC UF Baby-R Season 1 Privateer's championship.
And from the stuff I was watching via streams I remember most the incredible 2010 (? correct me if I'm wrong) Masters of Endurance 24 hour race which was won by just over an DT in the last hour.
Well, As I've done basically nothing in LFS... It's fairly easy.
1) Leading 12 laps of the 2nd round in STCC. Hannu Pinola crashing into a wall, me taking over the lead for him to chase me down and pass me. Then for me to crash several laps after that and flip. Starting my infamous run of inversions in STCC.
2) Placing 2nd in the first CTRA race. I know placing 2nd isn't normally a big deal, but the first CTRA race ran, after the "X System" was launched, placing 2nd was fun. Also the whole experience of administering the CTRA with SamH and others was a great time (when it wasn't frustrating as hell because retards).
3) IGTC, SamH and myself participated in it (with the other UKCT wankers claiming they would also actually drive ), and it was a blast. 4 hours around BL1R or Fern Bay, chatting on TeamSpeak about whatever and just having a good time. Not worrying about placing first or last, just having a good time. (I recall my Fern Bay round ending in a collision and shooting off into outer space
4) LFSCART this season. I know I'm late to the party, but learning the FO8 and enjoying it has been a rewarding experience. Sure I'm still shit slow at it, but it's fun.
EDIT: 5) I remember crashing into Scawen when they did that LX month several years ago. Also a while back, racing with Victor in the Fordman server was fun too
I'm sure there's more that I'm missing, and hopefully more that would be added to this list in the future. GT World Series is one event that I really would love to participate in, be it a driver, safety car driver, rescue car, or commentator (or any mixture of the 4 ).
Team BR vs Afri-Cola in a online race at SO long......First race, I finished 5th to qualifiy for Pole for 2nd Race.
2nd Race started on Pole, with team mate Krak behind me and he protected me all the way...to my first win online in competition....I had sweaty palms, you name it...was just awesome.
Some others:
Downtown Movie with Joecool
We raced all night movie with Joecool
Running 1st and 2nd season with ESL (used to be only Germany had this privilege)
Creating Triple 7 Racing and seeing it go from strength to strength and still going strong
Being part of a fantastic community which I never had on any other game