Masonry layout is only an experimental grid flow setting on Firefox and Safari at present and no good for production as not enabled by default.
You might want to revisit in one year and see if things have changed in the CSS space, see:
For now a symmetrical grid is the only sensible alternative, otherwise you are getting into having to use Javascript to deliver that. If you really want to go that route, you can look at the open source code in Topic List Previews or Topic List Thumbnails and adapt it for this use case.