I know this isn't the place for discussion, but I'd like to throw my opinion out about a few mods that other people have previously suggested.
Soul Shards: While nice, the newer version has a lot more limitations from the previous versions, not the OP kind, but make it less controllable and interesting. The creature spawning feature is already covered by MFR and there are some alternative mods that could offer more and interesting features along with this if needed.
More Pistons: I'm a big fan of this mod, however don't feel it has a place in most FTB packs, purely for the fact that the 3 tiers of drawbridges in Tinkers' Mechworks cover most of these pistons' features already. Adding it in a pack where Mechworks is already featured would just be starting to bloat the pack unnecessarily in my opinion.
Steve's Factory Managers: While I've not really used this to its full potential yet, I like it. It gives a lot of options for automating and doing a lot of things, is made by a familiar mod author, fits in well with several other mods in the packs, and I feel would be widely used.
-------------------------
Mod Name: Dimensional Doors
Link to Mod:
http://www.minecraftforum.net/topic...rsal-dimensional-doors-v141-eyes-in-the-dark/
Version: 1.4.1
Reason(s): This mod is feature-complete and offers a lot to the average FTBer. Firstly there's the exploration aspect, trying not to get lost as you delve deeper into worlds, avoiding monoliths, and picking up some cool loot along the way, the option to create your own dungeons also would be great for FTB and open up a lot of new possibilities to make these tougher and more rewarding the deeper you go. Secondly, the doors themselves offer an alternative place to live with a void world, getting rid of most of the tick lag most people have when having a thousand and one machines in the overworld along with mobs spawning outside and everything else going on, could make for a good server hub or similar things without the need to delve deep into Mystcraft first.
Mod Names: Redstone in Motion / Truss
Link to Mods:
http://forums.technicpack.net/topic/45317-16x15x-redstone-in-motion-redpower-frames-2300-october-8/ /
http://www.minecraftforum.net/topic/1852349-truss-mod-rp2-style-frames/
Version: 2.3.0.0 / 32
Reason(s): RedPower frames, what more can I say? While Calclavia's MFFS does a great job of offering similar features, it's still limited, requires a lot of power, isn't included in some packs, and offers a bunch of features that most people never end up using (although I do appreciate that a lot of people do make use of it's main features). Both of these mods offer great alternatives and a lot of possibilities that MFFS alone can't do, frame quarries (I assume that's what Direwolf's doing with MFFS in his next SSP episode), moving bases, tearing apart landscape, etc. and a lot of compatibility with other mods so you can keep your system set up without it breaking.
Mod Name: Mekanism
Link to Mod:
http://aidancbrady.com/mekanism/
Version: 6.0.2
Reason(s): This offers a lot of technology and features that are already covered by other mods, but in a different way than most FTBers are used to. While it's moved away from being a solely UE mod, it still retains it's prettiness and features that made it what it is; jetpacks, robots, 5x ore processing (okay, may be a bit OP compared to other FTB mods but it can always be tweaked with configs), zombies and skeletons having more armour so it takes a little more to kill them with all of your super duper powerful modded tools and isn't too difficult early-game, more power generation, and a lot of integration with existing mods in packs.
