David:

There is no single weed killer that is "best". There isn't even a single weed killer that will kill every type of weed. You need to know what weeds you have, and what will control the largest number of weed types in your lawn without harming your grass. So, a great start is to identify the weeds that need to be killed, tell us what type of grass you have and work from there.

Also, weed killing is a temporary solution. If you don't fix the problems that allowed significant numbers of weeds to invade your lawn, they'll be back for sure.

If you are growing a healthy lawn, you really shouldn't have to spray weed killer on the whole thing. The occasional spot treatment of problems is all you should need. Weed-b-gon works well on most broad leaf weeds but doesn't do anything to grassy weeds.

ok well here's what i did that worked with weeds.
1. last yr had a dandelion problem, used a 'weed hound' tool to remove them before they went to seed. Worked great, this year i have hardly any!
2. this year the weeds seem to be mostly clover and chickweed. I used weed b gon max to spot spray, after 7 days they disappeared. So every week i got hunting for new weeds and this stuff seems to kill them off before they seed. Just make sure you wet the weed, too mcuh and the grass will go a little yellow for a day or two, but if you just wet it, it does nothing to the grass. good luck!

Personaly, Im a big fan of 2,4-d. Just make sure it wont harm the type of grass you have. As far as I know, only people who have St Aug(floratam, saphire) can not use this herbicide.
You can get a gallon of concentrate at tractor supply. Get the ester varity, it seems to work a little better.

This is the main ingredient of almost all weed killers and weed b gone knockoffs.

I have a large area of turf in a rural area that alwys will get some weed infestation. Usually I spot treated with 2,4 or a similar product. But this Spring did tried a new product6 and it was fantastic!

It is SpeedZone. It works very well in cold weather. I used just less than 1 oz. per gallon in a hose-end sprayer over the entire turf area. It is rain-fast in 3 hours.

After 1 week the chickweed, henbit, etc., that was starting to take over was completely destroyed. I then fertilized in mid-March and with the warm April weather the density of the new turf and lack of competition has filled in completely.

After the first application, there was some yellowing of the ends of the blades of the fine fescue in the lawn. But after 1 mowing it was back to normal. Also I advise not use use a surfactant or adjuvant with this product which may reduce it selectivity on broadleaf weeds only. Also, I would not get it near shrubs as the product can be absorbed from the roots and damage the plant.

In mid-April I inspected the lawn again and spot treated with the same product for late germinating weeds. I used less than half of the amount of liquid I would normally use to spot treat at this time of year. With spot treatment I noticed no yellowing of the grass blades.