Each packager brings a fine technical and aesthetic sense to his or her product and each product reflects that sensibility in its makeup. I can't/won't say who is best I don't think that is possible. Many names in this list link to distribution web pages where you can find further pointers and instructions.
They strive for installations that “just work.” Go to the G'MIC home page, scroll down to 'Teams' and, among the 'Contributors' listing, look up those who have the ‘packaging’ specialty by their names. There is also a small but very fine community of packagers who take great pains to integrate Gimp with its large train of plug-ins and extras, including G'MIC. Use apt-get, emerge, yum or whatever else manages your distribution's repository. These have been tuned and integrated with the distribution and could be a better fit than the generic binaries at the download site.
If you use a GNU/Linux distribution, the standalone G'MIC interpreter and gmic-qt plugin are very likely in your distributor's repositories.
