I was surprised how strong Hydralisks are against siege tanks - TeamLiquid tells me that tanks are actually strong against Hydras.
But why? Tanks do 35 damage (+splash) in siege mode to hydras. But their rate of fire is very low. Thor isn't any worse, and also provide air protection. Marines (with Medivacs) should work even better.
So questions is:
- What is really good counter to hydras?
- If tanks, then how to use them properly?
Edit: (after Tzenes's answer)
Pure hydras are rare, usually if you go pure marines eventually you will get Banelings. So you could use some marines, but don't think a lot of them is very good, only if you are able to make them in unexpected manner.
Regarding tanks: shouldn't Thors be much better than tanks against Hydras? They are almost twice more expensive (300/200 against 150/125) and has a little bit longer cooldown (1.28 against 1.04), but has 2.5 times more HP (400 against 160), 60 ground damage against 15 (in normal mode) and provide good anti-air. It is even better if you consider splash damage in siege mode too.
What do you think of that?