My primary concern would be that the baby not get dehydrated. Even if he is a good eater, he needs the fluids from breast milk/formula. Can you still nurse or pump or have you already started drying up (from not nursing)?
How many bottle brands did you try? Some times you have to try various types of bottles and nipples. I suspect he dislikes the plastic nipple more than he dislikes formula or milk. Bottle feeding is a different feel and he has to adjust to it. We had good luck with Playtex bottles. Also make sure the nipple is the right speed; at 10 months, he's probably needing a fast flow.
You can also try pumping and putting breast milk in the bottle, to help with the transition. YOU should not be the one to give him the bottle initially. He knows you have "something better". Someone else needs to be the one to work with him on the transition.
I've heard that its important that the formula be body temperature in order for the transition to work well. If it's too cold, he might spit it out for that reason. And pre-made formula (instead of the powder) is supposedly smoother, less gritty.
By the way, both my daughters are allergic to cows milk protein and they drink goat milk. But I did not introduce straight milk until 12 months.