One other factor to consider when using a subscription based backup service...
If you let your subscription lapse then you will almost certainly lose your backups. This won't affect your primary data (i.e. what you are backing-up) and it shouldn't affect any local backup (e.g. to a USB disk), but any data which depends upon that subscription (e.g. data stored off-site, probably in the cloud) will be lost.
CrashPlan users can find information here about data retention at the end of your subscription, the TL;DR version of which is "you've probably got about 2 weeks grace, but don't chance it". Other backup systems are likely to publish similar information.
If you use a subscription backup service now would be a good time to check the subscription expiry date, top-up if needed and set a reminder in your calendar about the future expiry date.
This post was brought to you by bitter experience - thankfully not mine.