$re = '/<(?:[^\d>]+|:[A-Za-z0-9]+:)\w+>/m';
$str = '<@108012418998792192> (User)
<@!420279649055145996> (User)
<:oof:463391326491377674> (Emote without number in name)
<:Tyler1:311344841466576896> (Emote with number in name)
<:1234:123412314353463456> (Emote that just has number in name)';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php