It's easy to get both marks and gear, you get the same rewards from lv36 strikes as you do heroic, drop rate may be slightly higher on heroic, not sure but most of my good drops came from lv36, I've gotten more than a few pieces of blue gear that were 295-300 and most of the strike specific gear. Every mission is soloable as well, even fear's embrace (though that one really sucks solo). If you are having issues with gear grab a bunch of three of coins and go grind the lv36 strikes for an afternoon or night.