Best ways to deal with every raider

Cloakbots:
Every glaive that slips causes damage. Take them all out, hunt them down. Recommended turrets: Lotuses, pickets.
Shieldbots:
The bandits are slow, and they are easy to detect. Any unit is effective against their clumps. Recommended turrets: Lotuses + radar
Rovers:
Scorchers are less effective in numbers. Expect little harassment. Recommended turrets: A pair of lotuses.
Tanks:
Kodachis can take a beating. Prepare to beat them with brute force, execute stragglers. Recommended turrets: Stardust, newton, stinger.
Amphbots:
Ducks' damage is guaranteed. Expect to take losses. Recommended turrets: Lotuses.
Hovercraft:
Daggers either take the encounter, or they don't. Take them out before they get close. Recommended turrets: Pickets.
Spiders:
Fleas are easy to shrug off, venoms die to fast skirmishers and riot. Recommended turrets: A lotus.
Jumpbots:
A pyro is slow and expensive. Skirmishers are effective against it. Recommended turrets: Lotuses.
Gunships:
Locusts act like a normal raider, except more expensive. Beat them with counter-raiders! Recommended turrets: Lotuses.

Note: This thread only covers ground battle.
Feedback is appreciated.

any sane raider player will attack turrets only, if there is a chance to win. anything can be overrun. so, suggesting turrets as "counter" to raiders is wrong in itself. it is an expensive safeguard against smaller numbers. raiders speed is the key to your demise.

- katastrophe

Pickets are definitely not the thing you want to defend against raider, lotus is the most effective in the two, in any case of raider except blastwing (or puppy?).
The most important thing about countering a raid is having your own raiders in front of them, in such a way that they have to chase you if they want to attack, and if so, they will lose much more than you. Even better if you can take them in a pincer so they cant retreat.
If they go past you and they are in your back, you are in trouble. Lose some mex if you have to but don't chase them, try to circumvent them again, going around to place yourself on their way, again.

Having lotus + your own raider is very effective, attacker have to get rid of lotus asap but your raider prevent it.

Map topography also decide if you can afford a few riot on key access or if you have to have more raiders to cover all the front and be more mobile.

The best advice I think about is 'have intel'. Always have radar all around to see what's coming, you can guess what's coming by the speed of radar dots.
Also scout to see what's your enemy is doing:
-if he spam raiders and not much eco, while you were doing eco, he will overwhelm you. in that case, stop expanding and immediately spam lotus, retreat con. when he comes to you, you will be ready, lotus being more effective, meanwhile send few raider in parallel to his base (unnoticed from him if possible), he will have nothing for defense.
-inversely if he's doing only eco, spam raider and rush him

For almost ever raider I'd say lotus is good enough at key spots.

For fleas every cluster of Mexes needs a lotus

For scorchers you need to change it up and focus on radar and really plan your base around being able to reach raiders with your own raiders or riot units. Scorchers are unique in that if you don't have legs they will park right next to your turret and deal max damage. That's why one scorcher can beat a lotus but still not be very exceptional on raider V raider.

Pickits offer almost no raider protection.

Largely agree with katastrophe's analysis with the caveat that I did say that raiders need to be dealt with away from valuable stuff with units. The problem with having zero statics is that if you fail to deal with the raiders effectively, and two glaives slip through, they can do a hell of a lot more damage to an unprotected base than the cost of a Lotus.

I would go a step further and say that the cost in APM to drag units back to deal with stray raiders is very detrimental to a game. Instead of microing your own raids you now have to try hunt down the raiders before they pick off a fusion or a fac. If you have some light porc at the backline you can usually ignore stray raiders and concentrate on killing the enemy at the frontline.

I've seen games that have been won at the start by players getting raiders into an unprotected base early and as a result the expansion of the raided player completely stalls as they try to catch the pests.

pickets have only 3 shots... you would need a large picket investment for this to work.
If the raiders run in, lose 1 glaive, spot the riot and run away, they only lost 1 raider in exchange for your investment of the picket (does not make cost)+requires a riot to be there...

Cliver5, trust me that Pickets are almost never worth the effort. Their damage is just too low. If they had unlimited missiles they would be useful but they don't. A swarm of fleas can easily deal with a few pickets whereas a couple of Lotus carve fleas up. Pickets are really useful in denying swifts overpass and in towering up against lotus in isolated areas. The moment mobiles with a bit of hp enter the equation Picket becomes junk again. And this is coming from an old school Pulveriser enthusiast.

The only good thing about pickets is it has a lot of LOS.

Not too useful on immobile unit though.

Yes, and you can win without dropping your factory and doing anything at all if your opponent resigns just so.