The "better horse" is on maternity leave. That's why I'm riding these other monkeys. I point blank told my instructor a year ago that I will stop riding if she puts me on anything other than the angel mare and she agreed to let me ride only her. I sound like a horrible person in this thread, maybe I should quit venting on you, poor forum people :)
Well... I am going to go against my previous reply and say this: if you only ride one horse, a horse who's "an angel", your riding won't (can't) get any better. Not to say that you should be on a bucking monster of a horse, but after 3 years of regular riding, you should IMHO be able to handle a horse that isn't "an angel". Horses all have their moments, and their bad days, just like people. No horse is perfect 100% of the time. If you don't ride other horses, you cannot possibly become a better rider. Sure, you can be a decent rider, but you won't be able to ride that angel of a horse forever, so yes, after 3 years of riding you really should be on other horses.
IMHO, a GOOD instructor will put you on many horses. They will push you. Lesson horses should be safe, however they cannot all be dead to the world or "angels" either. You do need to advance at some point, and honestly, if I were your instructor I'd say no more "angel" horse (unless you truly need
a dead broke/dead to the world babysitter horse like that).
And, I really don't mean this to be rude at all, but if you're only willing to ride one horse ...when will you ever ride the horse that you own? Not sure how long you've owned yours for, or the exact reason you won't ride it, but if you truly don't think you are a good enough rider, then there's a bigger issue here. Is the horse you own too much horse for you?