I'm another Streamlight fan...
Based on your needs I recommend either the ProTac 2AA or 2AAA.
These lights run on easy to find AA or AAA batteries, are thin enough to carry in a pants pocket, have high/low/strobe options, and are tough as nails. I've been EDCing one of these two lights for years and have had no issues. Cheaper lights will not hold up to everyday use.
You will find the modern LED lights will surpass the lights of yesterday in output and they do it in a small package. They are bright enough to blind an attacker, yet will dim down for times when you need less light.
I also have one of Streamlight's ProTac-HL lights which runs on 2 of the 123 batteries and cranks out 600ish lumens of light. I have found uber bright lights have their place, But they are too bright for everyday use. They are the light if you want to light up the yard or blind an intruder. As such, mine sits beside the bed for things that go bump in the night.
Edmo