I play both and have nearly every expansion since Wrath when I actually made my first alliance ( was Horde in Vanilla and BC). You largely make your own play experience.
That said, it is vastly more easy to find pug groups as Horde especially the higher up you go. I’d also wager the average basic competence level is higher on Horde. You can generally bet on a pugger just being a better overall player in any tier of content.
On the other hand, Horde is absolutely more filled with elitist donkeyhats and bullies and elitist wannabe bullies. Again though, you can do a lot to curate and craft your own community and more or less insulate yourself from the downsides of either side or just with people in general.