I think you first have to decide what your “must haves” are for the tablet. Screen size/resolution? Low price? Tech support? Etc.
Assuming you meant “Surface 3” and not “Surface Pro 3″, the screen sizes are different. Cube i9 is 12.2″, Teclast X3 Pro is 11.6″, and Surface 3 is 10.8″, all with similar resolutions. Also, I’m guessing the prices you quoted for the Cube i9 and Teclast X3 Pro do not include the keyboard cover, which adds to the total cost (assuming you intend to use the keyboard).
I wanted a 12” screen, so I bought the Cube i9 during a sale last month. The total cost for both the i9 and its keyboard cover was about $450 US. I think it’s a decent tablet, but it’s not a Microsoft-quality tablet. I’m not sure I would buy it again given the chance, but part of the “fun” for me was experimenting with a Chinese tablet. The Core M processor is nice, but I think it depends on your use-case scenario for day-to-day use if you would notice a major difference from the x7-Z8700 found in the Surface 3.
Plus it’s easy to return a product to Costco if you decide it’s not fast enough for your use.
.
