Can I only upload Favorited images and videos to Icloud so that it shows on my devices?

Hey Saul-!

I believe with iCloud Photos turned on, anything in your library will sync.

You could however also upload photos separately to iCloud Drive if you needed to.

Likewise, you could, if you needed to, create a new photos library on your Mac, enable iCloud Photos, and make the new library the System Library, syncing everything from the new library to iCloud, (However if you wanted only this one album to sync with iCloud and not others, you can delete the existing photos from iCloud, and only sync this library with iCloud).

There are also Shared Albums, in which members of a Family can share photos in a special album meant for the Family, without sharing any other photos.

Designate a System Photo Library in Photos:

https://support.apple.com/en-us/HT204414

How to share albums in Photos on your iPhone, iPad, and Mac:

https://support.apple.com/en-us/HT202786

Others may have more ideas, Hope that helps though!

The easiest way to have only your favourites on your other devices is to create a small Photos Library to be used for iCloud Photos, as DiZoE suggested. I am using this approach successfully, on all my Apple devices, but a bit differently from the procedure outlined by DiZoE.

We can have several Photos Libraries (Create additional photo libraries in Photos on Mac - Apple Support). Only one of them can be the System Photos library, and only the System Photos Library can sync with iCloud and can be accessed by other applications, like Pages or Safari.

So we need to create a System Photos Library with all photos we want to be able to access from other applications and to sync to our other devices. My System Photos Library has all my Favourites, and all recently added or imported items that I am currently working with. This library is small enough to fit onto my system volume on my Macs onto the iPhone and iPad.

I am keeping copies of all older Photos Libraries on an external archive volume. There are all my photos and videos, not just the favourites. When I am importing new photos, I am also importing them to the archive library. This archive with all libraries is regularly backed up by cloning it with Carbon Copy Cloner to a backup drive.

There are many advantages of using iCloud Photos:

• It is a perfect sync.
  • When I add adjustments to a photo or video on any device (iPhone, iPad, Mac) the item will be updated on all devices.
  • When I add captions, they will appear on my iPhone as well.
  • When I add new photos on any device or delete photos, the library will be kept identical across all devices.
  • The albums and folders are synced
  • The locations and named faces are synced (depending on the system version)
• It supports all media formats of the new iPhones and iPads.
  • Live Photos and videos and Portrait Mode photos are transferred correctly.
• Your Photos are stored off-site. You can recover them from Apple's servers, if you Mac should get lost or stolen.

But switching to iCloud Photos will not give you a full backup with a history. iCloud Photos is always showing the current state of the library. You still need to make regular local backups of your Photos Library and the photos you are storing in iCloud to be able to recover accidentally deleted photos. As long as you do not enable "Optimise Mac Storage" for your iCloud Photos Library, your regular Time Machine backup will include the Photos Library and your phots, as they will still be mirrored locally on your Mac. Back up the library in Photos on Mac - Apple Support

Shared albums and My Photo Stream are sadly limited, compared to iCloud Photos. My Photo Stream cannot transfer the edits and metadata, and does not transfer Live Photos or videos at all. Shared albums are reducing the size of the photos and stripping many metadata. Manual import from the iPhone will just transfer the photos, not the albums, and manuals syncing to the iPhone is not fully adding the photos to the library but keeping the synced albums separate, with many drawbacks.