yep i know many prefer the missile pack. My experience so far was that the combined shots of 4 missile drone and the HRR was a good combination.
First i always like the little extra punch the DS1 shots give me against vehicles. These +2 on the penetration table (which is easier to reach thanks to S8) are quite effective and brought many vehicles to explosion in my games. Also their instant kill ability against most marines and other TEQ stuff brings me a little smile every here and there in the game. "Sure you have armor safe..., but not for these two extra hits."
Second with its longer range the HRR in this number can cover pretty much the whole table. So there is not much hiding my enemy can do, even if he stays out of 36"
Third, if getting assaulted, two sync HRR shots together with 4 sync plasma shots at BS2 all ignoring armor safe are pretty deadly, keeping in mind, that most units assaulting don't have cover safe anymore. Also if one of the pathfinder teams get assaulted every broadside team can give them overwatch and the range helps.
And last and propably the most important reason. I love the old broadside model with its HRR and hate the new one. So yeah HRR is my way to go
Like I said, I combine drone net and ranged support cadre. So no riptides or hammerheads. The HRR is pretty much the only weapon against high T and high AV targets and i have good experience with it. If there is anything a tau army has too much its S7 and 5/5 weapons
Perhaps its also because its not a single broadside but six of them. In my opinion the HRR gets better if you have more of them.