I rage quit once when one of my gregtech machines exploded out in the open. Caused an explosion larger than a nuclear blast, Greg seriously needs to nerf that or add a config option for it.
Ended up deleting that world. The next world I did was a huge 25x25 shack in a wasteland. There was some TC3 stuff in the middle with random machines along the walls. My TC3 node reset and I rage quit. And then my next one was supposed to be some kind of messy cave with lots of TC3 magic-themed stuff in it. It actually turned out to be some crazy tech-themed base with lots of spires of railcraft tanks of oil going up and down, genuine flashing lights (actually hooked up to some useful system, and they actually meant things, rather than just being random lights hooked up to timers) and stuff. Then my 7000/7000 aura node in that world disappeared and I deleted the world, in a huge rage. The next world was supposed to be totally perfect, in a mystcraft age. As it turned out, I actually got lost and couldn't find my base again. So I rage quit there too.
My current world is a GT hardcore one with 0% cheating (besides Mystcraft, I really hate it's system of getting pages so I just bypass it) and it's going quite well. Mining is a lot easier than I originally thought it was the last time I actually did manual mining. I have some basic stuff set up in a village, as well as a small 8-roomed 2-story villager hut for me to get more villagers. Some cobble buildings with nice vanilla village-themed aesthetics are expanded upon the rooftops, and I have a room dedicated to each mod.
I wonder how this world will end. Probably when I make a mystcraft age and enter it without a linking book back to the overworld.