Perspective - main differences between time series chart and XY chart?

What will our client gain from us choosing to develop with one chart vs. the other? We’ve been using the time series chart for a while now, but some of the complaints about it have been a lack of grid lines and other minor stylistic things.

We chose the time series chart because we thought it was the better chart for historical data over fairly long time-spans. After 6 months using perspective, I’m still unclear the advantages one chart has over the other.