If you're searching for players for your guild, there's a tool here that will let you search anyone who appears in the hero power, titan power or arena top 50. This is going to be most effective on newer servers as everyone with any kind of power will be in the top 50s, and less effective on older servers as active high powered individuals will be outside the top 50s while people who stopped playing are still visible. In short, this is a good tool for recruiters to find paying players who recently joined the game.
As an example, here's a search that includes myself in the results.
You can click through to the player's server to see where they sit in the overall results. Many guilds in this search won't actually link to a guild on this site, as guilds do not get added if they are not in the top 3 leagues or activity top 50s, so if you find a guild with a missing link this probably means you found someone in a solo or very low activity guild.
This tool allows a recruiter to make a query something like "show me all the players in Japanese guilds above server 500 with power over 3 million who are in gold". Being limited to only players in the top 50s it is not perfect, but it is incredibly useful.
As this site has been so much work to put together, access to this tool is only available to patrons, via Patreon. You need to make an account here, then message in discord with your username and I'll set your role so you can see the player search. I'm in Australia and this is a manual process so it may take some hours.
If you are simply trying to encourage players to join your guild rather than actively seeking them out, add a recruiting pitch to your guild. Guilds that have a recruiting pitch or who have some variation of "recruiting" in their name can be filtered on the main guild lists with the selection "actively recruiting".