Link your pally/Ranger magelos - tbh its possible your not taking a few things into account itemization wise/AA wise (not doubting knowledge or anything) but your ranger should not be able to tank 6 with the stats you posted earlier. Hell 6 will dent my warriors health and hes a t7 tank. Link the magelos and lets have a look @ them, constructive criticism never hurt.
as far as pallys go tho - we are defiantely having 0 issues with ours so sounds more like its something on your side man.