It really just depends on the people like I mostly just use iMessage to like play iMessage games but what's the time like if it must not a group chat on Snapchat so I really just depends on the people
I enjoy group chats on iMessage a lot more but iMessage is like for family and group chats, Snapchat for like individual friends that I'm not really close to.
Me personally, I'm a grown woman, so if a guy asks me for my Snapchat, I'm just gonna block him immediately. So I say iMessage. I'm not using Snapchat. I use that in high school.