Yes, MTG is a good choice for AIIMS GK.

Another book you could refer to is :-

• Aim4aiims GK book by Dr. Ajay Mohan (AIR-6, 2011)

Also, I'd like to mention that the GK in AIIMS is quite general and you can do it easily so it's better to give more time to other subjects rather than GK as GK is not the main subject of focus in the exam. Just keep yourself updated with the current affairs and news. You can easily crack the GK part. 

Hope it helps.