Fenix - Made in China. I dropped a Fenix once and it broke. They would not fix or replace it and told me too bad. This was about 7-8 years ago. Their service policy might be better or worse now, I am unsure. It soured me of the brand, and I dont buy them anymore.
Streamlight - older stuff/more expensive stuff made in USA. Lots of newer stuff made in China. No questions asked warranty. I sent in a broke Strion, they sent me back a working Strion a few days later. I sent in a 20 year old non-working Stinger, and they completely rebuilt it with all new parts and sent it back to me in a few days. Great company. Great warranty.
Surefire- made in USA. Expensive. Good warranty. I've only broken two switches and they send new switches no questions asked without having to send it in for repair. Decent company (not as good as they used to be), good warranty.
Malkoff and Elzetta - Lights built like tanks. Wont need a warranty, because it wont break. I have an Elzetta that is 10 years old and it is a beast. Always works. Period. No questions asked warranty should you need it.
What is the better quality light and why? They seem very comparable and in the same price range. I'm having a hard time finding out if Streamlight tail buttons can be lightly pressed for momentary on/off without actually having to click it.
I like Streamlight over Fenix every time personally. Almost every Streamlight I am aware of uses the light press on the tail button to turn on momentarily, full press to turn on.
What is your price range? What kind of light are you looking for? ... so we can offer some advice.
My opinion is that Surefire is better then Streamlight or Fenix. Streamlight is better than Fenix.