You havn't phrased your question well, do you mean in a one on one context, as dps in a 2v2, 3v3, 5v5 context, or in a raid dps context?
Since you specified T5-6 i'm going to assume you mean raid dps, in which case rogues should win, most dps charts put rogues near the top, and paladins somewhat further down. Retri DPS is still a little lower than other melee dps, however they have some good utility (extra buff, 3% raidwide crit, possibly keeping up JoW and JoL) which means one retri can operate well in a support-dps role, but multiple retri pallys in one raid is uncommon, whereas multiple rogues is usually essential.
If you mean in a PvP context, as the second half of your question implies, then once again rogues are the great allrounders, they have plenty of stuns and interrupts, so should be able to take a pally of any spec one on one. A holy pally is very resilient and may be able to nuke you down, a prot may be able to porcupine you to death, and a retri may get lucky with some big crits + procs + judgement + crusader strike and almost oneshot you., but in general a well played rogue has enough tricks to win.
In a team PvP context the rogue is a better allrounder, and operates better as sole dps or one of two in 2v2/3v3, the retri pally has excellent burst damage, which when combined with other dps (a rogue stunlock, warrior MS etc.) can be very potent in 3v3/5v5, but they don't operate as well as lone DPS.
Edited, May 14th 2008 6:35pm by Tinyknight
Edited, May 14th 2008 6:36pm by Tinyknight