If free trial never existed but having a chance to get free gifts to spend first 2 months
My first raid could have been Icecrown Citadel and Ruby Sanctum during 3.3
But I ended up to have Blackwing Descent and Baradin Hold with my cousin
But BWD and Baradin Hold were amazing
Zul’Gurub I think it’s called. And it sucked. All I did was spam flash of light.
I tanked Kara back in TBC with a small friends and family type guild.
Then in Wrath I did some Naxx, never finished it as we were too small and couldn’t always get 10. We’d try to recruit in friends from other guilds to help when we could.
ruins of Ahn`Qiraj in Vanilla, was bloody awesome. On my warrior as an offtank with a nice guild
My favourite raids are the Wotlk expack though, I kinda went abit hardcore there and cleared all raids and getting the legendery axe on my DK aswell, loved it
Did the first bits of MC, ZG, and AQ20 with my Vanilla-guild, slow going (Never got past the first handful of bosses until RL obligations forced me to leave) and not very fun.
But in BC i did full runs of Karazhan (Late in the expansion, after the emergence of badge-runs), first on my warlock (To get familiar with the place), and then MT-ed it a bunch of times, that was fun, i’m still very fond of old Karazhan.
Molten Core 
at lev 56 lol. My guild forced me to farm the fire resistant gear half green half blue 
Still remember to this day. So many memories 
Timewalking Black Temple to get the glaives in late BFA. My first LFR was season 4 SL so all SL raids pretty much, I don’t remember which exactly was my first.
ICC was my first. Started playing in Last patch of TBC but never had the balls to try join a raid till ICC. I miss that raiding guild, it was a small family guild, tank and off tank where farther and son.
molted core … back in vanilia and we didn’t clear it 
because 40 people in a raid was pure chaos 
but was primerly a casual guild we killed a few bosses but it was hard to motivate people to do the whole raid
Molten Core. Back in the vanilla days.
Was it amazing? No. It was fun at the time to play with friends, but I hated that place.
Terrace of Endless Spring.
A friend of mine invited me because his guild was doing it but one of their guys had to leave. I was the replacement in a group of 25 players.
I was in full PvP gear with a PvP build and I didn’t know the boss mechanics, nor did I know a PvE rotation at all. I managed to get 3rd place on the damage meters for the first two bosses.
As expected from me, I bragged about it in chat in a very obnoxious fashion and I got kicked from the group before the third boss.
I remember it fondly.
Bastion of Twilight.
Got kinda ruined, 1 because the 2nd boss singled me out with the debuff causing my inexperienced ar** to wipe the raid… repeatedly…
Two, was forced to use my buff on another warlock who wasn’t too pleasant because it stacked.
Karazhan and Zul’Aman because it was a small wholesome guild and we didn’t have numbers to go 25 man. Good memories.
Wotlk Naxxramas. It was my first raid, and I have both good and bad memories of it.
It was amazing.
I killed a few bosses here and there in raids if a friend was needing a body but it wasn’t until TBC that I started raiding as endgame. And it would be Black Temple.
O…M…G the bosses Gorefiend and after… Especially the Council. It was not so much amazing as brutal.
But my first amazing raid was Naxxramas, and my all time favourite raid would be ICC if not for sentimental reasons with my old guild leading everyone to get their 10 man and 25 man meta mounts.
And of course running people through Shadowmourne.
Ahh those were the days before my guild self imploded during Dragon Soul leaving a very bitter taste in my mouth which still remains today.
The best raid there ever was back in WotLK,
Vault of Archavon, with a Pug!
Or Naxx with the guild.
HAHA they were all like that in the beginning. Just glad to be there after the attunement grinds. No video guides the odd written on Thottbot or Wowhead, no voice. Core, BWL, Ony, Naxx,etc you didnt clear in a week if ever :).
with my amazing 56k modem back then thottbot would have loaded to slowly anyway businesses generally had have single or double ISDN but it was far more common to have 28k or 56k modem good old dailup
this kids and their crapstic (classic) wow have it good they dont have to play at 2000 ms
does going with a raid into BRD count?
Any instance with more than 5 ppl should count.