Any opinion on which is the best afetrmarket head to buy?

I have seen a number of them with differnet theories on why they are better then the competators.

1) Pivot trimmer-- 4 splines which pivot and are suppose to have less breakage when striking hard objects
https://www.pivotrim.com/

2) Grass Gattor trimmer head--

3) Hurricane Trim & blow-- Both trimms and blows the grass clippings away so no need for a leaf blower.
http://www.youtube.com/watch?v=KxBQws4c-dc

4) Echo--has a universal attachment with quick thread. thread a 8" piece of line throught the hole

5: Shindiwa--speed trimmer head

Open to other

I am looking for a head that trimms accurately & cleanly cuts the grass without mashing it & tearing the top of the blades of the grass.

What type of line would you recommend--thicker or thinner. There is alos round, square, serrated and cross ( i.e.----> + ) types lines

FWIW I just bought some Oregon Nylium Starline string for my cheapo Farm and Fleet trimmer. The Arnold Maxi Edge I used before was awful. It would fuse in the head, break off inside the head, and not cut clean. I heard the Nylium Starline is tougher.