I've always been using the japanese word ばか whenever i message my 恋人. Same goes with くま. These two are always present in our convo. I guess I could say these are my favorites.
Right now it's るいすい because it keeps showing up in my Shiritori Cat games, but also I love all the echo-y words like that. ひとびと and ときどき also come to mind. I'm a simple little guy.
I like the word え, you can use this word for many things. likes when you impressed, confused, agreement, asking back all with one letter 'e' . -Insert markiplier E memes here -