Selecting which of the three options is right for you is an individual choice (you can give yourself the most options by staying enrolled in the MGIB).
GI Bill Decision Timelines
MGIB: eligible Airmen wanting to disenroll must do so upon entering active duty.
Post-9/11 GI Bill: do not have to make any decision about transferring from the MGIB to the Post-9/11 GI Bill right now (decisions can be made between 90 days after completing technical school and time of use).
GI Bill Resources
DVA: information on all GI Bill programs at http://gibill.va.gov or call 1-888-442-4551.
AF Personnel Center: find answers to questions about transferring to the Post-9/11 GI Bill at https://www.afpc.af.mil/Benefits-and-Entitlements/Post-9/11-GI-Bill/
Summary
The two GI Bill Programs are the absolute best educational programs ever offered to military personnel. If you are undecided about your educational goals or you feel you may change your mind, then you can keep your options open by staying enrolled in the MGIB.
However, if you disenroll in the MGIB, it is a permanent decision and this is your only chance to enroll in the MGIB. Do not limit yourself … keep the door open for whatever education path you want for yourself or for possibly transferring those options to qualified family members someday.
Take your time and make an informed decision that is right for you.