With my son, he was picky about which sippy he liked, and then during the day I'd only give him his milk with the sippy (he's on solid food now so he doesn't need the formula as much) and only gave him his bottle at night and he transitioned really well that way. At the start I also bribed him with something sweet so I put a little bit of watered down apple juice in the sippy to get him to want to learn how to use it to get the yummy stuff.

If he'll drink from the sippy only give him the sippy during the day and a bottle at night 4 right now. Then ease it a way all together

He uses sippy cups but he prefers the bottle. We’ve used all different kinds. Don’t really have a preference

I had to go through that least 3 types of sippy cups before my son liked it. Which brand and type are you using?