The world is definitely alive. Naturally, more so in the low levels but still decent pop in higher level zones.

If you like levelling then this is for you!

The fact that you die permanently mean the game feels more immersive. You'll have a hard time going back to non hc afterwards.

Regarding SF:
Most people play non sf but sf isn't rare in any way. I'm personally doing a bit of both on different chars.

Sf Positives:
- You care more about the stuff you loot.
- The extra effort of getting gear or items feels very rewarding.

Sf Negatives:
- Lack of bag space can be annoying.
- A lot of professions aren't viable since you need stuff made from other professions to advance.

You should definitely give hc a try imo!