Hi Spilfish,
Unfortunately, we can't recommend anything for third-party products. You can compare the two models (BDP-S3700 and BDP-S6700) here and also find out the differences by entering the two full Xperia model names: https://bit.ly/3yptRsF.
Sony Support EN

This was a gift I chose based on data, reviews and cost. To my knowledge, the recipient is satisfied with it.