If there is no distinction between the content of the left and right columns, in other words if they are all similar or completely unsimilar where two groups are not made out, then the second layout with equal gutter (spacing) size vertically and horizontally is better.
This is because space is used to help relate or disassociate things. If consistent space is used, the items are associated. If there are inconsistencies, in most cases it disassociates some from others.
In the case of your example, more vertical gutter makes it seem like there are two groups - those in the left and those in the right. Since this is not your intention, you should avoid this layout.
One other note is that it would likely be better to have a consistent vertical margin between the top of the section containing these tiles and the dot buttons below them. As is, it looks somewhat like there may be something missing or that there is more space than intended, but it is minor in comparison to having inconsistent gutter space among the elements themselves.
If you think there is too much empty space around the elements for some reason, you could fill it by making each tile larger or by adding some extraneous design elements which would give the page more style.