QH's are great beginner horses in general because they typically have calm even dispositions...but again, it ALL depends on the horse, that's just a generalization. There's a 14.3hh QH at my barn who is VERY strong and requires at least an intermediate rider, but then there is a 17hh TB who ANYONE can ride, so you just never know until you go check the horse out.
Definitely check out and ride several of them, and then ask the seller about a 2-wk to 30-day "trial period" in which you get to keep the horse/ride/care for the horse and see if you two would be a good fit for each other. Many sellers will allow at least a week or two trial period once you've found the horse that you believe is "the one".
How very exciting for you, congratulations on becoming a horse owner!
Another website to check out (and where I found Sandie, who is ALSO my very first horse) is www.equine.com