MassPlanner so far is my favourite tool.
It has its learning curve, but it's not noisy and fancy like other web based tools and it's pretty straight to the point and it seems to be working ok (at least for me and a lot of other people, just don't over do with the auto following and likes).
Still, there's a lot to things to fix for the scheduler and I don't know how much it would cost you to run 50 accounts (you would need a vpn, massplanner subscription, massplanner instagram module, proxies etc).