You can use 2, 3 or 4 columns masonry grid. Each image in this gallery type will be resized to the same width and images will keep their ratio. Gap between images is fully customizable, you can use whatever value you like (examples below comes with 30, 5 and 2px gaps) or use grid without any gaps. Masonry is also fully responsive and can be used on standard pages and as a full width gallery.

2 Columns Masonry

3 Columns Masonry

4 Columns Masonry