Thank you for reaching out. As you mention, new products are being released all of the time and it is difficult to stay current with the latest hardware offerings.
From the Collector product perspective, I can say that we do see a wide variety of devices being used and it can be quite difficult to choose what best fits for your organization.
A few key considerations with tablets:
1. GPS - unlike a phone, most tablets do not have a GPS chipset included unless you purchase the WiFi + Cellular model. That may be OK for your needs as you can supplement the location capability with an external GPS as well but good to consider as it adds to the price.
2. Rugged vs Non-Rugged with casings - varied opinions here. You obviously are going to pay more for rugged devices than non-rugged and this can be a very personal choice for an organization.
3. Platform and your IT group - your IT department *should* have a policy for mobile devices, most do. They may be restrictive on platform, they may have an MDM for configuring apps that can work inside of the firewall, etc. Best to reach out ahead of any purchase.
I can tell you that for user adoption with Collector:
Apple Platform - iPhones out number iPads almost 2:1. Apple does not provide us with details on the specific iPad models but from the customers I have spoken with, the 10inch model seems to be the sweet spot. Not too large and not too small. Apple adoption also far outweighs Android adoption.
Android Platform - a lot more fragmented when it comes to devices, as you would expect. However the most used manufacturer is Samsung and the Samsung Galaxy tabs are most commonly used with Collector.
I hope this helps. It would be great to hear experiences/thoughts from users here. I hope to see this thread grow!