I've started the following two and a half weeks ago with 2-3 friends on my own server:
Minecraft 1.6.4
Forge #937
-Alternate Terrain Generation
-Barrels Mod
-BetterGrassAndLeavesMod
-Bibliocraft
-BiblioWoods Forestry Edition
-Biomes O'Plenty
-Buildcraft
-Cloudmaster
-CodeChickenCore
-Forestry
-GraviSuite
-Greg's Lighting
-Immibis Core
-Immibis Advanced Machines
-Immibis RedLogic
-Immibis Microblocks
-Industrialcraft 2 Experimental
-Inventory Tweaks
-Iron Chests
-NEI
-NEI Addons
-NEI Plugins
-Nuclear Control
-Railcraft
-Rei's Minimap
-Stalker Creepers
-Thaumcraft 4
-Thaumic Tinkerer
-Thermal Expansion 3
-Tinker's Construct
-Translocators
-Twilight Forest
A lot of stuff is heavily custom-configured. Particularly the ATG/BoP pairing required a bunch of work and research to get right. Then the fact that I redid the entire ore worldgen config across all mods to make use of the full 256 world height. BetterGrass is heavily tweaked to enhance only that which BoP's plant growth doesn't supply. Many other mods have config tweaks to fit more seamlessly together. My aim was not a glut of features, but rather a world that feels like it's one single cosistent system instead of a content patchwork. If you wonder why your favorite mod is not on the list, it was likely a deliberate decision because it didn't fit in or provided only redundant content.
Issues I've encountered:
- I have tried 4-5 different extra dungeon mods, but they don't play nice with ATG and BoP at all. All these mods are blindly relying on the vanilla terrain generator and biomes, and fail to integrate smoothly with anything nonstandard. Underground structures spawning inside treetops or castles being reduced to chaotic clouds of floating debris on a steep mountain flank don't really add much to the game.
- While on the topic of BoP compatibility issues, Forestry's butterflies also won't spawn or even take flight in almost all BoP biomes. They spawn and fly fine in ATG's and Thaumcraft's biomes, so this seems a BoP issue.
- Immibis Microblocks got into a big conflict with TE3, as it attempts to still support TE2's conduits. This can be fixed with some research and new versions potentially don't do this this. I am also wondering if I can run Forge Multipart alongside (or instead of) Immibis here. Will decide later.
- Stalker Creepers is hilarious in multiplayer, especially on highest difficulty
But it also changes explosion behavior so that you can't "reset" the fuse anymore by breaking line of sight. That's a bit unfortunate because it leads to more random explosions.
- Greg's Lighting doesn't replace Wrathlamps as well as I thought it would.
Oh well, still better than installing the entirety of Factorization, which is a more invasive mod than you think it is, just to get a single item.
- ATG generates freaking amazing worlds. But be prepared for a resource-hungry server due to the way vanilla Minecraft handles chunk columns. Vanilla on average uses maybe a quarter to one third the available world height and thus "cheats" itself to good performance by having 60%-75% nothing in each chunk. But ATG can and will use the entire span from 0 to 256 for terrain. On average there's a lot less air in any given chunk, and all that "not-air" wants to be calculated and kept in memory. For me, it's easily worth it, because I have a beastly computer and ATG makes vanilla Minecraft worlds look like junk in comparison. Your mileage may vary!