Heartbeat looks expensive. I've been using TapMetrics (free for now) and AppFigures (fee-based, as beta ends this month) and I think I'll stick with AppFigures. AppFigures does all the downloading so I don't have to worry about it. iTunesConnect just changed something this past week, which broke TapMetrics' toolbar app, twice.
AppFigures now lets you choose which apps to track, so if you have freebies or low-selling apps that you don't want to pay to track, you can choose not to.