Currently, the reaction feature is mostly used for likes, but it's not limited to that. Here are the top 30 reactions my node has seen in the last couple of days (with counts):

["+",259104]

["🤙",141352]

["⚠️",1720]

["😆",911]

["🖖",504]

["❤️",433]

["😁",401]

["🔥",324]

["🍔",248]

["💮",196]

["😭",180]

["🤔",125]

["💥",117]

["🥂",109]

["⚡️",105]

["🤣",104]

["😩",96]

["👽",72]

["🐾",70]

["😮",69]

["🧐",68]

["🍮",58]

["👍🏻",54]

["😃",52]

["👑",51]

["🦴",48]

["👀",48]

["😄",45]

["😂",43]

["💯",37]