I can't think of anything. Support, product, design, functionality, value is all great.
ChartMogul shows us our core business metrics: MRR, LTV, ARPU, Churn, and more. Before, we were keeping track in a spreadsheet. Our data was never quite right, and it took time to update as we grow.
Now we know exactly what our metrics are, for zero effort. Everything has worked splendidly, and we aren't even paying yet. It's free for under $10k MRR. It seems to look/work much nicer than competitors like BareMetrics, and their free tier is a no brainer.