Nvidia's lineup is a mess of corporate bullshit designed for confusion, price control and to produce headlines. They are both bad, I tend to prefer the 3080 12gb because it was an incremental upgrade late in the product cycle that could supposedly replace the original (some like the msi are starting to move closer to the original price in the US market, they could always price a refresh like this slighly up, but reality is prices are all over the place so it's a moot point), while the 3080 TI was a stupid endeavor from the start in a normal market, it cut half the memory from the 3090 while delivering pretty much the same performance (sometimes more because of power budgets) for close to the same launch price of the 3090.
In my opinion it made sense to update the memory on the 3080, heck it should have had more than the 10gb from the start, while the 3080 TI was a pure cash grab from the get go. With the prices you listed, I'd go for an AMD card because of the silly low vram on the regular 3080 nvidia, if I catched a the MSI 3080 12gb at 830$ like it was recently or even at 970$ maybe i'd go for that, etc...
Pricing is crazy right now, but that doesn't mean nvidia has to make it even crazier with a disorganized and non sensical line up (I mean it's great for their pockets, it's all profit since the ones that have to deal with inflation on raw materials/discrete components and be called out for gouging are the board partners)
