Gen 2 much better. The RF 24-105 has IS, is light and portable, your mirrorless has much better low light noise control. I have pics in LR from the EF 24-70 Gen 1, the Gen 2, the RF 24-70 F2.8, and the RF 24-105 F4.0 (plus a lot of other lenses.) The RF 24-105 lives on the camera almost as much as the RF 100-500.
"No doubt the two Tamron lenses will give you great results." Yes, this is a fact. They some are very good. As an example I don't know if I would choose the Tokina AT-X 16-28mm f/2.8 Pro FX Lens over my Canon EF 16-35mm f/2.8L III USM Lens but there is no doubt I would take it over my Nikon AF-S NIWatch on When it comes to a walkaround lens, you generally have two options: a 24-70mm f/2.8 or a 24-105mm f/4 (or something similar). So, which is right for you? Both options have
Nikon AF-S FX NIKKOR 24-70mm f/2.8E ED Vibration Reduction Zoom Lens with Auto Focus for Nikon DSLR Cameras $2,097 Nikon AF-S FX NIKKOR 24-70mm f/2.8G ED Zoom Lens with Auto Focus for Nikon DSLR Cameras
Let's test the new Canon RF 24-70mm F2.8 lens against the EF 24-70mm F2.8 Mark II on two sets of different images. We'll look at images produced using the CTamron’s image stabilization (VC) works exceptionally good. The Tamron had serious vignetting issues at 2.8 (along the whole zoom range). At F4 and above vignetting was no longer an issue. In the center of the frame Canon’s lens is always slightly sharper and at 24mm the edges were significantly sharper than the Tamron SP 24-70mm f/2.8 DI