What is best dandelion killer?

https://gardenambition.com/best-dandelion-killer/

Literally, getting on your knees the minute they pop their little leaves out and digging it up making sure you get entire root.

Here's a tutorial and recipe http://homeguides.sfgate.com/homemade-natural-dandelion-weed-killer-44593.html

There are weed killers that will not kill the grass, just read the labels and see which ones are safe for grass.

I pour boiling water on them then dig out when dead.

"SpeedZone" will kill broadleaf weeds like Dandelion and also clover but not kill grass. Follow instructions carefully. A stronger than recommended mixture will yellow grass. Spray on individual weeds if lightly infested or on the entire grass area if heavy.

I would dig them out or pour boiling water on them.