The MIT license is the less restrictive of the two in terms of complying with the license. For example:
"Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software"[1]
the GNU license on the other hand states:
"You must license the entire work, as a whole, under this License to anyone who comes into possession of a copy. This License will therefore apply, along with any applicable section 7 additional terms, to the whole of the work, and all its parts, regardless of how they are packaged. This License gives no permission to license the work in any other way, but it does not invalidate such permission if you have separately received it."[2]
Other conditions under the GNU license make it amenable to guarantee that additional work added to the code is maintained within the open source community. That is not a requirement of the MIT license.
If you are contemplating licensing under any of these licenses it is advisable to consult an IP attorney.