When enchanting an item with say, 25 percent reduction off illusion spells, if you use the same variables i.e. same soul gem size and same enchanting potion, as well as having the extra effect perk, would fortify magicka and fortify magicka regeneration offer more or less the same effect, but with every magic school?

If only there wasn't an rather thorough wiki (http://www.uesp.net/wiki/Main_Page) that will run you through the calculations.

The calculations don't show the whole story. You need to think out the results.

Fortify magicka (and regen) affect the magicka available, but it gets used up at a rate dependent on the cost of the spells. To cast continuously, you need one of two things: either the spells cost nothing, or you regenerate magicka as fast as you use it up. If you think about it, for a steady state, the total magicka makes no difference at all, it only comes into play when you're using more than you regenerate, and eventually stops you casting.

So for continuous cast, Fortify magicka is completely useless. Fortify magicka regen has to be high enough to match your most expensive spell (which it can't ever be if you don't reduce costs). Fortify (Magic School) can reduce cost to zero, and is the only viable method. But it only applies to one kind of spell, so chose wisely!

Note that the enchantments don't consider spell level, the way the perks do. Four items with the 25% level of Fortify Destruction will let you cast any Destruction spell without cost.

thanks so much, i had assumed reduce cost would be the better option, as had used them on another character, but only for two magic schools. My next character, you see, is going to be a nightblade type, so i wanted to use 3 magic schools, ( illusion, destruction and alteration,) so i wanted to use magic regen, but i guess i can drop alteration anyway, and i only need destruction for fighting dragons, but anyway thanks for the help!