Trying different bits/bitless

So my mare who I got recently has always had issues with bits. I tried a baucher on her (my gelding uses the blue shires sweet iron lozenge baucher and it fits her) and she really liked the stability of it but just didn't really like the idea of a bit. I tried a D-ring and she didnt mind but when pressure was applied she really didnt like It. Her teeth where done before she came to me, before we could pick her up the rescue did her worming, feet, teeth, vaccines (any they could do). So I know that's all done and not a teeth issue. When I went to try her she had a o ring with roller. She really hated the instability and movement. I tried a sidepull and she went amazing. What have other people tried for horses who don't really like bits? (I won't be using anything with leverage or gag action, baucher isn't a leverage). I'm currently sewing some padding and waiting for high quality foam to arrive for my side pull because I really don't like how there's so little padding. I want to do eventing where for competition I will most likely need a bit, but if she doesn't ever want a bit I won't compete. Comfort>ribbons