I got a 1070 Ti around the time the 2070 came out. I do not regret a single euro I spent on it, it OC's like hell and reaches 1080 performance.
Since the 2070 is around 1080 performance, I'd suggest you get the 1070 Ti (and the strix got a nice cooler) and overclock it.
Feel free to look for oc'ing guides if needed, or reach out to me.
edit : 6GB of VRAM is enough for 1080p ultra, I never filled my 8GB of VRAM on my 1070 Ti, I play 240Hz 1080p