We test on a range of phones such as Samsung, Motorola, LG, Nexus, Sony, etc. Very popular among blind people is LG Wine Smart - Android smartphone with standard keypad consisting of buttons which works smoothly with COrvus.
We have found some limitations when testing on HTC phones. In general it is not good idea to install COrvus on the cheapest phones from untrusted producers. It will probably work but probably not. It’s always better to send query or test before buying such a cheap phone.