Compression travel bags v ziplock freezer bags

[upsofloating]

I'm travelling on Ryanair with only a backpack (one of those Cabin Max ones you can fit lots in) and wondering about compression bags. I don't mean compression cubes or vacuum bags, neither of which I want, but this sort of thing:

Packmate 4 Piece Travel Roll Storage Bags | Robert Dyas

Does anyone have any experience of these (or comparable ones), and do you think freezer bags with 'zips' would be just as good?

Freezer bags won't work as they seal but do not compress or save space. I don't know about the robert dyas ones but I got these compression travel bags and you just have to let the air out (you don't need a vacuum or pump).

Thank you so much for replying, YourKindAmberCat. Very helpful and much appreciated.