I have always been a pretty strictly vanilla player. Optifine, nothing else. I play on a server that a friend runs, and it's vanilla too. Dicking around in creative is only allowed on the roof of the nether.
while i am looking for a server, this topic is here because i feel that no one plays "minecraft" anymore they play "technic" or "raiding/factions" or the spend all there time building "towns" ever sence i first installed mods i got bored fast, technic is to complicated/overpowerd, minecolony is way to buggy, and dont get my started on hack/mine (feels like wow or something), i just want to play vanilla again, like the old days of beta...
Thats what I've been doing. I suggest you get the better world generation mod because you can generate the old beta terrain, but still have access to sprinting, hunger, enchanting, etc...
I enjoy the natural feel of vanilla SSP but some mods look fun too and I'll probably try some soon. I doubt mods will ever be a replacement for vanilla Minecraft, at least not for me. It's like another gamemode: another way to enjoy Minecraft just as much but in a different way.
As for SMP, I prefer server-side mods that improve the social atmosphere and prevent griefing. Also, no pvp for me, thank you very much. It's hard to find servers with certain characteristics and there's plenty of trial and error finding the right one, but I assure you that they're out there.
vannila server were kinda killed by world guard when they added the ablity to ban items it ruin the game and player rather play on raid/factions cause they work together and most them dont have item ban like the vannila ones do
Anyways, I still play vanilla, or mostly vanilla Minecraft. I've always enjoyed building things in it (though I find creative mode too easy, and, thus, boring). While I do like Industrial Craft, I also enjoy SMP, and I've found a lot of players (some of my friends among them) don't like modded Minecraft. Thus, my server remains (mostly) Vanilla, save for a few "diversionary" mods that people seeking a break from building can enjoy (like MobArena).
And while I'm giving my opinion here, I'd just like to say that the idea of turning a game which originally seemed to be about building and creating into a destruction fest (IE, PvP/Raiding/etc) is the sign of a sick mind to me.
Or maybe it's just people giving in to their baser animal instincts. Whatever. They can continue stabbing each other with their *ahem* swords. I'll keep right on building.