Add
Hydraulicraft and/or
Calculator, and/or maybe
Pneumaticcraft and/or
FLORA/
FLORA Reborn.
Hydraulicraft may have duplicate functionality/power system but nevertheless is a cool mod, only appearing in Direwolf20?? Calculator is a really cool mod, adding all sorts of new content and things to work towards:
https://github.com/SonarSonic/Calculator/wiki. Pneumaticcraft has really come a long way from where it began, so you should definitely consider it for an addition. FLORA/FLORA Reborn is a really cool armor mod including fluid based armors, but you would need to include alternative crafting recipes for the required fluids.
EDIT:
QuasarCraft looks interesting for magic, haven't played, seems new, but the update looks like it will add content
For an alternative to Tinkers Construct Crafting Benches-
Werkbench
Arcane Arteries(Cool Addon for Blood Magic)-Change Razor Blade to be EssentialCraft 3 knife, adds support for EvilCraft
EvilCraft-Cool magic mod, looks really creepy (There is retrogen)
Magical Instruments-Looks cool, early/late game help against monsters
Magneticraft-Looks foreign, but has a power system based on Blutricity?!?!
I second Compact Machines
ChaosCraft 2-different kind of magic mod??
Floocraft-Cool teleportation(HARRY POTTER!!!)
Pressure Pipes-Might be redundant?, but infinite fluid transport
Ars Magica 2-Hasn't been in any 1.7.10 packs ):, but kind of unstable, and few updates?(Think there is retrogen)
Magitek-Different kind of magic mod, blatantly states tech, but presented as magic
JewelryCraft-Cool baubles, debuffs/buffs