TL;DR at bottom.

• I like stronger and more deadly scavs if only for the sole reason that it means we can have better rewards from killing them, and meaningful combat throughout a raid since most PMC action dies off just 20 minutes into most raids.
• I'd rather have the current Killa who always spawns with his valuable armor and consistently great loot rather than the old Killa who could be stunlocked by a naked PMC with a 12K SMG but half the time dropped garbage armor worth nothing (not to say that you can't try a Killa challenge with 12k of gear today, but it's definitely going to be harder now that he actually shoots back).
• I prefer having scary bosses like Sanitar so if I hear gunshots I think "oh boy there could be some juicy rewards there, I should go check it out" because PMCs may actually die trying to fight him, instead of the boss being the equivalent of a Ledx with legs where a player who spawns 2 minutes closer gets first, effortlessly clicks the scav to death, slurps up all the loot and is long gone before I get there.
• (For bosses in general, I'd rather have 5 PMCs scrap to the death for 5M of potential loot, rather than 1M of guaranteed loot for the first PMC who had the closest spawn and the next 4 don't even bother coming because the action's already over. Call me a battle royale degenerate, but a battlefield of corpses and loot that lasts for half the raid seems more fun than map-spawn roulette.)
• I think I would actually like regular Scavs to be even stronger than they are today, but they should also be more rewarding because more of the map's loot should spawn directly on the scavs. After all, if I find a bandit that has been pillaging expensive stores in a shopping mall for days, shouldn't I be more excited to see what's on his body than the plundered toolbox or filing cabinet beside him? And if I ransack a building to find that there's barely anything worthwhile, shouldn't I naturally assume that the big loot's been relocated in some hidey hole hidden cache somewhere?
• To be clear, if a certain loot spawn is gated behind a locked door which requires a key, of course it should stay as gated loot. But for all other types of loot that anyone can access just by walking to it and picking it up… since PMCs are showing up well after these bandits, shouldn't a lot of the treasure be the type that you must take forcefully from them?
• Loot can be more dynamic if we literally give it legs. That way PMCs don't feel obligated to run the exact same optimal route to farm the same static spawns over and over again. Scavs become like honey bees, moving from flower to flower, transporting pollen randomly around the map. But be careful, because now they sting!
• Scavs should always be scary. Anyone who is armed in a lawless wasteland should be a threat. A malnourished civilian may not be as capable as an expertly trained paramilitary soldier in combat gear, but if they're healthy and strong enough to lift a gun and pull the trigger, they're dangerous enough to be scary.
• If I'm chasing another player while wearing a faceshield and class 6 armor, and some random hobo jumps out of a bush and starts shooting at me, I should not be thinking "haha hey look there's an AI here, no big deal it's pretty cute, just going to keep chasing this BEAR," I should be thinking "holy f**k this random human being that I did not even know existed just came out of nowhere and is trying to murder me." The crazy person potentially on an unstable cocktail of medication and contaminated moonshine should be a material concern at all times.
• I'm not afraid of randomly dying out of nowhere to scavs. That's how most of my PMC deaths (and my kills against other PMCs) usually go anyway. It's just that since there's no consistent meaningful upside reward to regular scavs, I don't want to be inconvenienced by them. But if more deadly scavs that can kill you out of nowhere more frequently also means that scavs can become a direct source of map loot rather than just a distraction from punching boxes open, then by all means Head,Eyes me daddy.

TL;DR:

I think scavs should always be a scary threat, but killing them should also provide better rewards. Peaceful scavenging should still be a viable/profitable raid strategy, but I should be more excited to loot the bandit I killed rather than the trash bin beside him. Loot locked behind keys should remain gated, but a lot more of the openly-accessible loot in containers could be shifted to the pockets of nearby scavengers who have been pillaging the area. Boss scavs should be messy war zones, and I'm perfectly okay with making them more difficult if they're also consistently scaled to be rewarding (e.g. today's Killa with valuable armor and always shoots back > yesterday's Killa that could be cheesed for kills but also often had trash armor drops)

I'm not afraid of scavs that can randomly kill me out of nowhere since that's how most of my PvP kills and deaths usually go anyway. If 90-year-old WW2 grandpa veteran scav can get lucky and randomly catch me with his vintage infantry carbine while squatting in a bush, I won't even be mad. But boy oh boy, if he doesn't get me, then I'm taking his precious antique belongings to sell to those edgy 4chan boys wearing Anonymous hackerman masks and I'll be drinking a shitload of moonshine tonight.