Sam Bourne Triology vs Michael Grant Gone Series

I picked up the entire triology by Sam Bourne and Gone Series(first two books) for very affordable rates and wanted to know if anyone has read it.

How is one compared to other? I know one is sci-fi and the other looks like a thriller still just wanted some suggestion which one to start!

I am in my late twenties and another question is of these are suitable for my age!

Thanks