Megalaunchers or several turrets?

Whats the general consensus on defense? Massive amounts of missle launchers or several plasma turrets? and how much of each is generally enough?

Most people go by ratios, and the total number would depend on the amount of resources you are guarding. Generally, you'd want more launchers per turret. This is to act as fodder so your attacker can't easily target and hit the bigger more expensive guns. There are no hard rules, and it's really up to you.

http://tools.ogamecentral.com/defence-calculator

good place to start

generally if you go with 100% turrets you will need millions of resources to be able to defend a basic attack effectively. Each defence only fires once per round. So if you build 20 Gause and 10 Plasma that is only 30 shots fired.... and only 30 items to absorb incomming damage from an attacker.

Adding a Mix of launchers/Light Lasers increases your odds of NOT losing any expensive Turrets in the first few volleys of an attack while also saving your resources initially at the beginning due to how cheap they are to mass produce.

As a noob, I found all my defense material destroyed three times by cactus. I didn't know what was normal, but since then I've learned to not build defense, since all that gets wasted. But instead, now I put all my effort into building up my planet production and research which can only be done by farming little abandoned planets... many fleets with small cargo ships, repeatedly... you don't even need any fighters.
That is when Clout pointed out to me the "scoring system" and that I broke 150 rating accidently... and I'm still there nearly. That's how I'm doing it. But now I have about 30 fighters so I'm ready for an acs lightly defended base raid now. Let's do it.