Originally Posted by A knack for horses
In the end, I think it will come down to which horse you are most comfortable with and which is better suited to accomplish your goals.
However, don't count out the 18 year old one. Usually, older means more experienced. He has more been there, done that experience, and has more training than the younger one. Older horses are great for first time horse owners simply because they know what to do (in most cases, there is the occasional crazy older horse out there)
I agree with this. My newest mare is 17 and still trucking along. Especially since you're wanting to gain confidence, I would say the older one might be the better choice. However, buy whichever one feels more compatible with you. 8 isn't exactly young and green, either.