I don't really have too much stake in this so I wouldn't really care either way but whatever it's worth, I think I'd stick with Theus. They both spent just about the same amount of time of their basketball primes in Chicago but Theus spent that time as an all-star level player, whereas Kirk was Kirk - really solid but never really next level.
If Kirk had been a part of a championship team in Chicago, or even one that did more than just advance to the second round one time, I could see giving him the edge on account of legacy status (sort of like picking Tayshaun Prince over Kelly Tripucka on an all-time Pistons roster). But unless we're just going for players that younger folks will be more familiar with, I think I would give Theus the edge on account of his production and skill level.