Where you store the photos is a secondary consideration, the primary should be getting all your photos into a single place, ordered, de-duplicated and with descriptions of what each folder contains. No, really, it’ll be fun. 🙂
That is where the work is, and where you get the benefit. After doing that you need to ensure that you don’t start saving photos to different devices again.
Create a parent directory, then underneath, directories called:
<CCYY-MM-DD>-<description of event/contents>
The more complete the description, the easier it will be to search in the future – so a single folder “2016-06-21 – day out at legoland” is better than a folder containing “summer 2016”.
You could use an external drive to do this – cheaper, or a NAS, the latter having other benefits, but obviously costing more.
When you have things sorted out locally you’ll know what space you need for a cloud service and can then back them up to whatever cloud service doesn’t compress them.