Instead of these "smaller than/greater than" tag signs, the guild rank should show under the player names, surrounding the guild name.

For example, these symbols could be used instead of the "<" and ">":

• *** for Guild Master
• ** for Officer
• * for Veteran
• = for Member
• | for Recruit

So player "Bob", an officer of the guild "Foobar", would have this floating above his head:
    Bob
** Foobar **
Or player "Alice", a member of the guild "Bananas", would have this floating above her head:
   Alice
= Bananas =

Other related, but less important, ideas:
The player has an option to disable display of these signs, so a guild master can go incognito to avoid many requests for invites.
Icons would be fine, instead of simply using characters found on any keyboard.
Different sets of symbols could be created and the guild master may choose a set for all players of his guild.