Needing Help With 3 Lens Comparison

[wcsmedia]

Greetings,
I've been trying to look for either video explanations, or still photo comparisons, and other articles online regarding three unique mid-telephoto macro lenses and I'm having a difficult time doing so, so I've decided to try a forum approach. Three lenses are currently in question for me:
1) Tamron SP 28-75mm f/2.8 XR Di LD EF
2) Canon EF 24-70mm f/2.8
3) Sigma Art 24-70mm f/2.8 DG DN

I already own the Tamron and it has been a magnificent lens for well over a decade now, but I'm needing some guidance regarding the other two lens against the Tamron. I love my Tamron lens, but like everyone else who takes the quality of their photos very seriously, I'm especially curious if the Sigma is significantly better. As mentioned above, I cannot find a comparison online regarding these specific lenses and I really want to know if the extra money is worth it. Something tells me the Canon lens may not matter and the real comparison is going to come down between the quality of the Tamron and the Sigma, but I could also be very wrong in that assumption. Thoughts and feedback are greatly appreciated! Photo comparisons if you own these lenses would be even better, but whatever you can contribute would be fantastic. Thank you in advance!