TestRail provides the possibility to assign Priorities to Test cases. But they are linked to the test case 'object' itself, i would say that the priority should be adjustable according to the Test Run. i try to explain it below.
I have a product with 5 modules ( module A, module B ... Module E) having number of test cases for each module. If i want to test module A in a 'test run', then i would select test cases related to that module and put them in the 'test run', i may like to test some of test cases from other modules in that 'test run' because i feel that it may be good if i do so, but the test cases from other modules have less priority than the test cases of Module A. Now this is something i can not do in Test Rail. i don't see any connection of 'Priority' with 'Test case' with out a 'Test Run'. A test case can have high priority in one 'test run' for certain 'mile stone', and can have low priority for another 'test run' for another 'mile stone'. Therefore a 'test case' that is selected for different 'test runs' can have different priorities at the same time.
This is something i would like to have i.e. A possibility to assign different priorities to the same test case according to different 'test runs'.