4784.
4781 I have never completely explored any magic mod before, so I can't give you any ideas about rooms for those mods :/
That's OK dude, I appreciate the thought! And I totally understand
@MrMonsterGuy18's point of view here - there's so much more to Witchery than appears when you first look at it.
In terms of space for rooms:
Botania will need the least, unless I put a Gaia guardian summoning area in there.
Thaumcraft, I'll need space for the Infusion Altar, jars and stabilisers; Jars need to be within 12 blocks of the Matrix, Stabilisers can be within a 25x15x25 area (5 blocks above, 10 below).
Blood Magic, full size altar is 23x9x23, but if I wanted an area for demon summoning in there that would be extra space, plus there's rituals to consider.
Witchery, the altar has either a 14 or 16 block radius in which to put materials to add the power; there are also ritual circles and equipment (kettle, spinning wheel) that can use altar power which need to be considered.