| steven kent |
if you want a great character, drop magus completely.
wizard/fighter gasalt for 3 levels (I prefer trapper ranger).
then wizard to 5 and then into eldritch knight until 10, AA until 12, then finish off Eldritch knight to 20.
the reason why this is a better choice, is because of anti magic field at a range with a full wizards spell list. it is literally the most powerful character I know of. think of being able to drop an antimagic field on a Litch, while still having great physical damage to kill the target.
but if you're set on staying magus then AA isn't a necessary choice. I would argue that you gain enough from the class to make staying pure worth while. max out your caster level and ignore imbue arrow since it slows the progression of your necessary class abilities. if the magus had a better selection of aoe spells then it would be worth it.
if you do choose to try the Eldritch Knight build, then you owe it to yourself to focus on conjuration school of magic, or divination school for the alternate school specialization. having control of the battlefield is much more valuable then damage, so keep that in mind while you choose your spell lists.