Right now, GE prices would indicate that making Prayer Renewals are fairly fast xp and still only cost about 18 gp/xp, which is still pretty salty. Alternatively, Super Magics are selling for WAY over GE med (I bought mine for nearly 15k a pop to get 99 last week) and even then, they're just slightly less xp and 21 gp/xp when compared to renewals.
Lastly, you could go old school and make Super Attacks for roughly 17 gp/xp with quite a bit slower xp. Throughout the entire summer with the Enlightenment Aura shooting prices of buyables up constantly, all Super Potions are pretty good to make because they sell for so high above med... People need to make their extremes and overloads, dontchaknow