My boy's a gelding, and I love him. He was a horse looking for a person and still really isn't the kind of guy to just work well for anyone... maybe one day when he's older and calmer, he'll fit the stereotype more, but for me he'll try and try. The couple of times I've had other people ride him, he fought them and had a hissy fit the whole time, though he did do (sorta) what they wanted.
I don't really prefer one over the other, but it happens that the three horses I've really 'clicked' with were all geldings. The studs I've worked with and I have had a good respectful relationship as well. It's all personality for me.
I think it's the particular horse, although I own 2 geldings. My one gelding is very sweet, gets along with everyone, same every day. My other gelding....my vet actually asked me if I was sure he wasn't a mare....AND THEN HE CHECKED! Said my gelding acted just like a mare! .........my gelding doesn't "do" vets. He's a pretty sensitive dude.
I've had 2 of each and loved them all. I was happiest barrel racing my last mare and the last gelding was the best trail horse I've had. But if you think you click with geldings, stick with that thought.
I don't have a preference either way. I've ridden geldings that made me want to scream and mares that were the calmest, most consistent horses I've ever met. Granted, I've also met mares that were royal pains and geldings that were big teddy bears.
It all really just depends on the horse as an individual.
I have had 2 mares and I loved them to death. Yes they can be a pain but I find that they have more spirit then geldings (not that I have anything against geldings!). I also rode a stud for a few years and he was by far the most laid back horse I have known. I find that it really depends on the individual, but I have a special spot for mares.
I worked at a camp that had a herd of over hundred head. We did lots of trail rides and beginner riding class stuff. I worked there almost ten years, my go to horses the ones that when a kid said "i'm scared" where all mares its been over 8 years since I left there and the really good ones that I remember are the mares. Now here in Montana, its a little different. Its all about the Geldings everyone says mares are a waist of time, mares are cheaper gelding are more a lot of the time its only that they are a gelding. And guess what here its the geldings that are better horses.
I have worked with lots of horses, mares and geldings I have worked with RANK geldings that were not worth anything, I have worked with "baby sitter" horses both mare and gelding. I think horses are like people, you have to take them one at a time mare, gelding, paint horses, appies, ponies, "Arabs". A good horse is a good horse.