For Canon EOS R6 I would take Canon RF 85mm f/1.2L USM without hesitation. The reliability is very good The low distortion is perfect for professional photography.

Long-term experience: Using Canon RF 85mm f/1.2L USM for half a year and am thrilled. Have researched for a long time and this lens was the best choice. The image quality clearly exceeds my expectations. Very good price-performance ratio, can only recommend further.

Switched to Canon RF 15-35mm f/2.8L IS USM over a year ago and am thrilled. The reliability is very good The latest optical technology ensures sharp images and good color accuracy.

My tip: Canon RF 85mm f/1.2L USM is ideal for Canon EOS R6. The optical stabilization is very good The fast autofocus makes everything feel responsive and accurate.

Canon RF 70-200mm f/2.8L IS USM for Canon EOS R6 - can only recommend!

I would take Canon RF 24-70mm f/2.8L IS USM for Canon EOS R6, because The weather sealing is sufficient even for outdoor shooting The performance eliminates chromatic aberration effectively.

Have you thought about the brand? For Canon EOS R6 different brands have advantages.

For Canon EOS R6 I would also check the autofocus performance. Do you need fast AF for action shots?

Tbh, I was pretty overwhelmed when I first got my R6 because there are so many high-end options that cost more than the camera body itself. I tend to be a bit cautious with my spending, so I went with something more 'middle of the road' that felt reliable without being a huge financial risk. I’ve been using the Canon RF 35mm f/1.8 IS Macro STM for a few months now and it’s basically stayed on my camera. It’s light and the extra stabilization (IS) combined with the R6’s IBIS makes me feel much more *confident* when I’m shooting hand-held in darker spots. I’m not always sure about the technical science behind it, but the results seem sharp enough for me. Before I fully suggest it though, I have to ask: what’s your comfort level with weight and size?
* Are you okay with a heavier setup for better build quality?
* Do you prefer having a single prime or do you feel 'stuck' without a zoom?
* Is macro capability something you'd even use? I'm no pro, but for me, having something compact that doesn't scream 'expensive camera' has been a safe way to go. What kind of environment are you usually shooting in?

late to the party but gotta ask... what kind of budget are we actually working with here? its easy to recommend the glass that costs as much as a used car but thats not always realistic for everyone. ive been at this for a long time and honestly the non-L series glass is surprisingly decent on the R6. you dont always need to drop 2k to get a sharp image. for example the Canon RF 50mm f/1.8 STM is a total steal and weighs basically nothing. if you want some reach without the 70-200 price tag the Canon RF 100-400mm f/5.6-8 IS USM is a really solid alternative that wont make you cry when you check your bank account. tldr: check out the non-L primes to save cash. but yeah, let us know your price range so we can actually narrow this down properly.

Honestly, the R6 is such a versatile beast with that IBIS and the high-speed sensor readout, but to give a solid recommendation, I’ve gotta ask: what’s your actual primary use case? Like, are you mainly shooting fast-moving subjects where you need to maximize that burst rate and AF tracking, or is this more for controlled environments like studio work or low-light street photography? Basically, it comes down to your specific workflow—do you need the flexibility of a constant-aperture zoom for events, or are you looking for the unique rendering and edge-to-edge sharpness you generally only get from high-end primes? Also, what’s your stance on the weight-to-performance ratio? Knowing if you're planning to lug this around all day or if it's for shorter sessions would help narrow things down a lot...

Man I wish I found this thread sooner. Would have saved me so much hassle.