I am 14 years old and I personally have two haflingers at the moment, a two year old and a nine year old, both mares. Surprisingly the mare that you think would be better,and more mature is completely bullheaded and has little respect for anyone and has a tendancy to beat up trailers, last year at my county fair she even broke a stall because she didn't get fed fast enough. But despite this she is better once you get on her back, but she has a horribly hard mouth and needs a confident rider(which I'm not) On a happier note she is a Special Olympics horse and is great with the athletes.
Meanwhile my two year old filly is much more polite,will stand patiently while waiting to be fed, doesn't run people over, and loves everyone. She went to the fair this year and didn't even kick at her stall despite the fact her grain was sitting outside the door the whole time. In fact she slept most of the time. I have also rode her before(really lightly) with a broken finger, she would spook at stuff,like expected, but she was really well behaved and in the 4 20 minute times I rode her she has impressed everyone at the barn I ride at(me included). Over all I felt more confident with her than I do with my older mare, mostly because she understands "woah" and will actually stop when you want her to. Overall I have great expectations for her.
This horse sound completely different right? I think is depends what kind of Haflinger you get. Both of them don't have a single mean thought in their minds but one has no respect...I think it was her sire who she got that problem from, that and she is too smart for her own good... I can't fort the life of me think of anyway to properly end this, I bet I didn't help you at all either, I'm sorry 'bout that.