Another source for quilt mags available for review is our public libraries. Our relatively small library carries Quilt World and Piecework. Back issues of both available to take home as soon as new issue arrives. Neighboring larger library in our free loan area has many more. A good way to sample before subscribing or just saving dollars altogether.
One of the two guilds I belong to also does the 25 cent purchase at the guild library table - money earned buys books for the library.
I think that inspiration (ideas), education(techniques), motivation(competition winners/pattern makers), production (free patterns), creative interpretation (designer interviews and their quilts), world news information(guilds, shows, products on the market) are components to look for in the table of contents. This can guide us to the type of magazine that will satisfy us, the proportion of each varies greatly depending on the mission/purpose the magazine producer has.