Three decision factors while creating this list:
- Quality of releases
- Longevity of the band
- Impact on the thrash metal scene
The bands are :

1
Reign in Blood Slayer

No need to discuss here. They never sold out and kept on releasing solid albums.

2
Bonded by Blood Exodus

Not having a dependent singer hurt them so much. It kept them away from the music scene for 12 years. That's the reason they are not number 1.

3
The Years of Decay Overkill

The most stable thrash metal band. I salute Overkill with making them number 3 on my list.

4
Rust in Peace Megadeth

Mixed feelings for Dave Mustaine. He disappointed me with some of the albums. At the same I love most of his work.

5
We've Come for You All Anthrax

Even though they are on the decline for the last ten years, Anthrax is still one of my favorite bands.

6
The Legacy Testament

Although they experimented with Death Metal a little bit, they are still one of the best.

7
Nothingface Voivod

Pioneers of techno thrash!

8
Pleasure to Kill Kreator

Kreator's sucessful career is still alive. The best German Thrash Metal band period.

9
Eternal Nightmare Vio-Lence

They only released 3 full length albums (if you don't count pathetic "Nothin to Gain" abum, it's actually 2). However, they had a huge impact on the thrash scene and they are active again. Hope they release a new album soon.

10
Act III Death Angel

Death Angel is the fresh sound of thrash metal. We're lucky that they rose from the grave after a 13 year absence.

11
Infernal Overkill Destruction

The ressurection of Destruction in the last couple of years and backing it up with decent releases made them raise higher in my list.

12
Game Over Nuclear Assault

Very underrated and unappreciated band. I love their unique sound.

13
St. Anger Metallica

The only reason these sellouts are in this list are their first four albums.

14
The American Way Sacred Reich

Underrated band. Unfortunately disbanded. What a shame!

15
No Place for Disgrace Flotsam and Jetsam

A nice second tier thrash band from Arizona. Another underrated band in my opinion.

16
Agent Orange Sodom

Not a big fan but I respect the band.

17
Suicidal Tendencies Suicidal Tendencies

They may also be a hardcore band but they released a lot of thrash metal albums. I'm a big fan of Mike Muir.

18
Beneath the Remains Sepultura

Their first 3-4 albums sounded thrash so they belong in this list. I have zero respect for the material they released after Max left.

19
Metal Church Metal Church

Maybe I shouldn't have kept this list so long because i was never a fan of Metal Church but they kept the thrash metal spirit going and they also released a couple of solid releases in the past.

20
Dances of Death (And Other Walking Shadows) Mekong Delta

My final choice is german progressive thrash metal band Mekong Delta. This band was actually a side project of the members of Living Death but M.Delta turned out to be much better than L.Death

Saint ANGER? WTF!?! si 'tallica ar trebui sa fie pe primul loc (sau ma rog...al doilea pentru ca Slayer fucking kicked 'tallica's ass over time) pentru ca este una dintre cele 4 trupe care au realizat genul Thrash Metal (alaturi de Slayer, Anthrax, Megadeth), DUUH, tipul care a facut lista si-a afisat doar preferintele lui, deci lista nu este valabila 'universal', iar sfantul furie nu are ce sa caute pe nici o lista de genul "best songs" PERIOD!

mio placut lista dar nu am observat st anger..
parerea mea e ca ride the lightning tata...e tatal thrashului...si [cu master si kill]