Automated appraisals really aren't very accurate. Depending on the algorithm, you can get widely differing values. I don't see how Estibot can value them the same or how DI values vte higher than suk.
suk is brandable and pronounceable, with several different meanings. vte's sole 'claim to fame' seems to be Venous Thromboembolism.
There are a lot of recent under $20k sales for 3 letter .com's. So DI's appraisal for vte isn't too bad.
sux.com sold for $24,000 last year at NamesCon. It sold to an investor. It's now on GoDaddy with a minimum offer of $227,500. suk is probably worth more, but you would have to be extremely lucky to get a 200k sale.
You're in pre-purchase, so you want to buy? Especially now, it just depends how motivated the seller is to make a sale.