Question Which of these two laptops should I buy ?

Honestly about the only thing the Acer has that the ASUS doesn't, is a higher refresh rate. The ASUS unit has practically identical specs in every other regard EXCEPT that it has a 12th Gen i9 rather than a 12th Gen i7. That could be looked at two different ways. One, it's going to have significantly better CPU performance, however, it's also going to tend towards having higher CPU temps because of it and obviously with a laptop that almost certainly has very similar or identical CPU coolers since cooling options are extremely limited in laptops, that could be a problem.

Gaming laptops tend to very often have thermal management issues even if you are very conscientious about always keeping the laptop on a hard, flat surface, so that nothing is ever able to block the air intake vents on the bottom. So in that regard the i7, which is certainly good enough to keep that 3070 ti fed with frames, might be the better option in the long run BUT the Acer unit is also like 500 dollars more expensive so really it comes down to whether you actually need the extra performance to the tune of an extra 500 dollars AND are willing to maybe deal with thermal issues due to the i9 at some point. I'd say the chances of that happening despite the fact that the laptop is supposedly "designed" to handle that CPU and graphics card are about a 50/50 likelihood. I see so many laptops that are supposed to be able to handle the thermal requirements of the hardware that simply can't do it when the unit is used for any kind of long gaming sessions, and that problem tends to get worse and worse as the unit ages, that I simply don't believe them anymore.

They only care if the laptop makes it through the (Usually) one year warranty period and a lot of times they barely do that before they start having thermal issues. Even so, at five hundred dollars cheaper, and the higher refresh rate on the Acer is not even something I'd look at as a plus in this case because the 165hz display on the ASUS is already extremely high, I'd be willing to deal with maybe having to hamstring the CPU somewhat by disabling some cores or hyperthreads if the BIOS allows for it or via other means if it doesn't, IF you have thermal issues later.

Either way, I think I'd be very hard pressed to want to go with the Acer considering it has a lower end CPU than the ASUS unit and is a lot more expensive.