What software to take images regularly

Hi People,

I am looking at datto product Siris Lite which essentially takes backups of your servers on a regular basis and puts it into a cloud.

Its £599 up front plus £49 per month for 250gb but essentially its a small microserver with software built in.

Can anyone give me a guide as to what everyone else is using?

I am looking to backup some flakey servers on a regular basis so that I can bring the entire lot back up in the event of a crash and new to ESXI so not sure what is available and what people recommend.

Thanks