I personally think that with a beginner getting a good all round horse with a good brain is better than getting a horse targeted at eventing. Realistically, a beginner may not be able to handle the intensity that is a trained/professional event horse. Which is why, I say look for a sound horse that has a good brain. I would not discount an older, sound horse just because of its age. You are looking for this person to get miles on them, not put miles on a horse.
That said, I know a lot of folks love quarter horses and feel they are great beginner horses. I tend to shy away from that. There are some great quarter horses but there are some very hot horses. I really like standardbreds, and if you can find one broke to ride or are willing to break a horse to ride prior to allowing the beginner to work with the horse they are great. As others have said, with beginners its less about breed and more about horse.