Is your GTI tuned? If so, and if burst acceleration is still a major priority for you, it's worth noting that--depending on where you commute--in many day-to-day driving conditions, there is a vast difference between the
3.3T and the 2.0T, and the difference is beyond what a tune alone will erase. (Tuners: by all means, feel free to prove me wrong!

)
Having said that, I had a tuned mk6 and a tuned mk7, and I'm still quite happy with the stock 2.0T RWD, though my priorities have changed. The comfort, handling, and utility are what define the Stinger for my money. You get that at all trim levels, and the "base model" is plenty opulent feeling. As you noticed, the 2.0T is very satisfying.
Curious friends and strangers learn it's a KIA and the facial expressions are priceless. Doubly so when they learn it's a base model.
Also, after having some fine-driving FWD cars, settling into the very well tuned stinger chassis is a revelation.
If you are shopping 2018 models, make sure you are okay with the somewhat limited rear visibility, especially if the car does not have the advanced driver assist/drivewise package with blind spot monitoring and rear-cross traffic alert. I believe this is standard on 2018 GT2s and all 2019 trims, but optional 2018 base, premium, GT, and GT1.