Really as similar as possible but I guess the must haves for me are:

• Dark theme
• Swipe to type ability (I usually tap but definitely want swiping as well)
• Searchable emoji’s
• Word suggestions

Nice to have:

• Text editing tools for moving cursor just one character at a time through button presses
• Clipboard button
• Copied text automatically becomes next suggested word the first time the keyboard is invoked after copying the text
• Suggested next word.