Hi there,
If you don’t require anything fancy and you are using lazy loading and optimization on all images on your site then the core Gallery Block is good for me. It may take some CSS to get it how you like,
If you need anything more, or just greater control or inbuilt optimizations then Envira and Modula get good recommendations. NexGen Gallery – we seen some issues with that in the past, where it hooks scripts into the footer has broken some theme options.