We have the whole range of mares at my University’s stud. I usually find the mares that are bred frequently or have a foal at foot/just weaned are usually more overtly responsive to the stallions (maybe they’re more hormonal). Two of the mares I use for lessons are awful on the ground when they’re on heat, they’re usually wonderfully behaved but when they’re on heat and lead to the stables (which is through a corridor with two stallions on either side), they prance sideways, wink, urinate, squeal and neigh and generally take a strong, firm hand to keep them in hand (something the beginners find hard!)
Thankfully, my mare is completely unresponsive to stallions. We tease the whole herd of mares every morning to monitor their heat cycle (which is always an interesting thing to watch) and my mare never changes in her response. She is not overly aggressive to the stallions but she always puts her ears right back and pulls her angry face (she has the best angry face ever!). According to one of the Sisters working in the hospital, she came in (when she still belonged to another stud) with an open wound on her face because a stallion attacked her, so I can imagine why she hates them.