Showing cool charts

I made a website that receives reports e.g a status of a machine, now I think it'll be a lot cooler to show some chart but I don't know what data should it presents.

Should I use line chart and show the generated reports for the past week? Should I use pie chart to show which machine is frequently maintained? 

Please suggest what a data should a chart represents to make it useful and informative, thanks in advise guys.

I'mma sleep now, wait for my reply tomorrow, cya guys!