It measures websites; Skomi also measures apps. Simple Analytics publishes no mobile or desktop SDK. If the thing you need to understand is software people install, this is not a comparison. It is two different products.
Behaviour comes in the same subscription. Heatmaps, session recordings and a feedback widget are Skomi modules, metered from the same allowance the analytics uses. With Simple Analytics each of those is somebody else's product, and the numbers will not join up.
One place for the whole picture. The interesting question is usually a join: did the campaign that brought the most visitors also bring the ones who abandoned the checkout? Two tools cannot answer that without an identifier they share, and neither of them has one.