Hi ian nicholson,
Thank you for reaching Microsoft Community.
Please note that in connecting the Surface Pro 7 to an external monitor, we should the USB-C port on the Surface. Based on the specifications provided on the pages you provided though, the VORSPRUNG® 12” Tri Triple screen shows that it also has a USB-C port that supports video. For the other option (Xebec Tri-Screen 2), it shows that it also has a USB-C port but not sure if supports video input. Both options though have HDMI ports which you can also use to connect to the Surface using a USB-C to HDMI adapter. It would be best also to contact the manufacturer of these external monitors to make sure that we'll be able to use these screens to the Surface Pro 7.
As a Microsoft support site, we aren't able to provide a single recommendation. We can assist with identifying if a particular model is compatible based on the Surface you have, but we work with so many manufacturers around the world that it wouldn't be fair or reasonable for us to say, "This one is our favorite". Other community members may be able to speak to their specific preferences and let you know why they feel that way, so we will leave this thread open for their input.
Kind regards,
Marrion