What effect increased skills for enchanting?

To simply put it there is 1 factor that determines the skill increase and that is the soul gem used. The higher the quality of the soul in the soul gem the more it will increase your enchanting while used. The enchant itself or the value of the weapon does not matter.

Enchants on the other hand DO differentiate in the the value increase (enchanting a weapon with banishing would increase the value much more then a fire enchant would).

A quick leveling strategy for enchanting (that works in tandem with blacksmithing) is to buy a lot of filled soul gems from a court wizard and a lot of leather and iron from a blacksmith. use the leathers and iron to make daggers, enchant the dagger with the most powerful enchant you can get (Banish, so it would be profitable to buy 1 banishment weapon and disenchant it but other weapon enchants would also work but yield fewer profits).

Once you used up all your soul gems enchanting the daggers you sell them to the court wizard/blacksmiths and then just save, quit and start again (resetting all vendors) so you can buy new materials to craft and enchant the daggers.

This will help you level blacksmithing, speech and enchanting in one go while also filling your pockets with gold :)