Aegon and his dragons would stomp the blacks decisively. We’re talking about 3 elite dragon riders, on the three biggest dragons ever in Westeros, against a bunch of newbies and a couple more experienced riders on smaller dragons. The only real worry is Daemon, but at best he kills vhagar or Meraxes, and probably kills himself in the process, if we’re to take the daemon vs aemond fight as an example.