As the author you can always re-release the code under MIT but once it's released under MIT corporations can whole sale rip your work off for their own profit. If you keep it closed source or GPL it then you maintain some breathing room from another company just swooping in and monetizing you code for their profit.
On the other hand, if you accept contributions while under a strict license like the AGPL but then decide to go MIT, you'll have to ask each contributor to relicense his or her work or remove that work altogether.
OP, if you see your project switching licenses down the road, you might as well look into CLAs, a whole other can of worms, or just stick with the least restrictive license that achieves your goals. I'd personally use LGPLv3.
