It is tough buying a horse when you are older and more breakable. Too easy to fall for the pretty face and believe you can work through issues.
A friend who used to show H/J had her horses age out and hadn’t ridden for a while. Then, when she was 72, bought a 17 hand green horse. It has not gone well.
I am on my second registered Morgan (had one partbred too) Partbred had been mishandled and was a nervous wreck on trails at first. Once he relaxed he turned into a super trail horse - alone or in group. Dont know that I would want to work through it now. Last Morgan could be spooky in the ring but became solid on trails and willing to go it alone. Current boy is spicy and talented for dressage. I havent had the opportunity to do more than walk around the property (no trails) but he does go away from the other horses alone and isnt upset. Obviously trail riding is not my focus (though I may switch stables and be able to get him out!)
Hopefully you can find a horse to lease that is happy to go out on trails alone. IME, it is more likely to be a gelding. And if you buy again, you need to be able to walk down the trail in your trial ride and day one at home.
I would forget about breed and concentrate on training and performance on the trail. Hope you can find a great partner. You never know. The steadiest trail horse I knew was an Arabian!