Trying to remember this off the top of my head, so I'm almost guaranteed to miss something. Also this will be roughly in order of the changes I made in the order I made them.
1: Moved FTB mods to the MultiMC loader. I really, really, REALLY like FTB as a pack. However MultiMC is a far better launcher. Being able to create backup copies of my instances, having multiple instances on multiple versions is just perfect.
2: Added Keysprint (I despise double-tap sprinting), Optifine, Logistics Pipes, Additional Pipes. Ripped out Gregtech, Thermal Expansion, Factorization, RailCraft, Steve's Carts and ComputerCraft.
3: Watched DW20's videos on TE, Gregtech, Factorization, RailCraft and Steve's Carts and ComputerCraft.
4: Added TE, RailCraft and Steve's Carts back in, also added EE3. Further solidified my resolve that Gregtech and Factorization aren't for me.
5: Restarted a new world to get TE worldgen and moved to a BC/TE base instead of an IC2 base. Removed ComputerCraft again. Removed EE3.
6: Updated to 1.4.5.
7: While trying to find an NEI conflict removed IC2, Gravisuite, Advanced Machines, Advanced Power Management, MFFS. Eventually found conflict and added IC2, and only IC2, back in.
8: Added Thaumcraft 3 with worldgen regeneration. Normally I'd start a new world but, hey, this is magic so those world gen items could very well magically appear.
Added EE3 back in.
That's where I sit currently. I am currently waiting on RP2 (who isn't) mainly for the gates and red alloy wiring. The rest I can do without. When it comes out I'll probably start a new world and probably remove IC2 and Steve's Carts. While IC2 is where I dove first when getting into modded Minecraft (I'm a late comer) the more I get into the BC base, the less I use and want to use IC2. I'll miss my drill and my Industrial Diamonds, that's about it. I tried 1 cart in Steve's Cart and it isn't for me. Not sure if I'll keep Thaumcraft 3. I will keep in EE3, for the time being. Depends on how far he takes it. But honestly, there are some things that are far harder than they need to be to obtain and I'm more than willing to destroy things, not even on an equivalent basis, so I can skip the annoyance. Ender Pearls, I'm looking at you.