Lens Choice: Canon 70-200mm vs. Sigma 150-600mm for ORD Spotting?

Hey folks, I've been trying to up my game in aviation photography and I'm torn between two lens options. I'm mainly shooting at Chicago O'Hare (ORD) and I'm debating between the Canon 70-200mm f/2.8 and the Sigma 150-600mm f/5-6.3.

I know the Canon is sharper and great for close-ups, but I'm worried it might not have enough reach for those far away shots, especially around runway 27L. On the other hand, the Sigma covers a huge range, but I've heard mixed reviews about its sharpness at the long end.

Anyone have experience with these lenses at ORD or in similar busy airports? Would love to hear your thoughts on image quality, handling, and overall versatility for spotting. I'm mostly shooting daytime, but I do want to try some sunrise/sunset shots too. Any advice would be awesome!

I'd go with the Sigma 150-600mm for ORD. The extra reach is super handy, especially around runway 27L where you might not get as close as you'd like with the Canon. Sure, the Sigma might not be as sharp at 600mm, but if you're mostly shooting in good light, it should be fine. I use a similar setup, and for sunrise/sunset, just bump up the ISO a bit. You might miss some sharpness, but the shot's worth it.

I'd lean toward the Sigma 150-600mm. That extra reach is a game-changer, especially at ORD where the runways are spread out. I've used it at other big airports and, yeah, it can be a bit soft at 600mm, but it's manageable if you stop down a bit. For sunrise/sunset, the Canon's f/2.8 would be nice, but you can work around it with the Sigma by upping the ISO. Depends on whether you prioritize reach or a bit more sharpness.

I'd probably go for the Sigma 150-600mm. The reach is just too useful for a big place like ORD. I have the Canon 70-200mm, and while it's super sharp, I often find myself wishing for more zoom, especially for those runway shots. The Sigma's not perfect at the long end, but if you keep it a bit under 600mm, it's decent. Plus, for sunrise/sunset, the extra reach will help you capture those distant silhouettes. Got any plans on shooting specific types of planes?