Personally i would either wait for the 4000 series midtier cards or just buy a 3000 series card with enough vRAM. However keep in mind that the 4000 Series theoretically could be worse or on par for machine learning than the 3000 series in some cases due to lower memory throughput: (https://www.reddit.com/r/MachineLearning/comments/xjt129/comment/ipb6p8y/?utm_source=share&utm_medium=web2x&context=3)