I could not advise you on what is the "best". You will find some information on the magnesium forum if you choose to do so. If you do a search, you will most likely run into lots of discussion and disagreement on what is best. Bottom line is you must make your own choices.
I truly believe that our best mineral sources are whole foods and herbs when grown properly, however it is extremely difficult to find properly grown and harvested foods unless we do it ourselves. This may be one reason I have found the alkalizing drink very helpful for me, providing a broad spectrum of minerals.