Running 29 will continue to work until there is some issue identified and fixed in a later version. Running 30 you lose the ability to filter OP_RETURN > 80 bytes. Running knots you get all the fixes applied to 30 and later plus you retain the ability to filter OP_RETURN size. But you can also turn that off if you want. To me knots gives me the most options. 30 removes an option that I wish to exercise. So for me, it's knots.