I prefer to play and run RPGs where combat is gridless.
I don’t hate grids, but I find they tend to focus attention on the table as opposed to the fiction between the players. Maybe that doesn’t happen in every group, but I’ve seen it happen, and I know it happens if I use a grid.
I think I also know why it happens.
Without a grid — even if you use floorplans sketched on paper, tokens, figures, etc to clarify positioning — fiction by necessity remains the primary source of information. Any visual aids on the table are just a map, not the territory. To understand the situation the group must refer to the fiction.
With a grid it very easily becomes the primary source of situational information. Fiction must still correspond to it, but as it becomes subordinate to the grid its importance is diminished, and there is a tendency to relegate it to mere fluff. The grid is the territory and the map in one.
I know some people play with grids without the fiction suffering. Reading about their games actually made this click for me: the umpteenth time someone mentioned how they re-incorporate everything that happens on the grid back into the fiction I realized that that’s my disconnect. I don’t have the discipline to do that consistently, and so fiction recedes into distance.
This doesn’t happen to everyone, but I know it happens to me. So I don’t use grids in my games.