My go to build for now was a Vengeful Avenger with Varangian Blood carrying an SMG and using the Field Medic first Peek to buff up the "when an ally is down" buff to its maximum.

Haha, that's a hilarious amount of overkill, nice.

Either way, do you know any decent source for weapon stats? I checked the wiki but it shows only partial info about items, weapon and the like.

No, the wiki's on this game, and all around info is very poor, but I know the game in and out and know the best weapons for every category and how to work the builds to get the most out of them, so just ask me anything. Had too much time on my hands.

I'll reflect briefly on a few things right now, and you can ask whatever you like more clarification.

...

First of all, don't even try to keep up with penetration, this game is all about elemental damage, that avoids it completely.

Second, I see you mentioning a lot of buffs and debuffs. Just wanted you to be aware that debuffs are strictly for RP in intentionally gimped builds. Rarely a fight should go beyond the first turn if you don't want it too, and like never into a 3rd turn unless you're just fucking around, stunning people and punching them to save ammo.

Now, be aware, that while I will be talking in terms of "optimality", this is all gross overkill what follows. My current run has a pointdexter barter guy with both modding skills for convenience sake and every ranger has a RP background and it's still crushing SJ, so yea you won't need all the things I write.

1. One ranger can/should be your fire smg guy and he wields a ripper with incendiary linkage, has +4% strike trinket for 34%. He will, almost without exception just melt everything on his first torrent strike. You can get a ripper by save scumming from a safe in Patriarch's villa, or your bunker from la Perla when selling Hallie. You can use Goat Killer, or Disciple of Metal as bg, and Serial Killer or Varang. Blood as quirks. Serial Killer is actually better, because it will stack with Trigger Happy and because he will kill everything in normal torrent strikes, he ABSOLUTELY doesn't need crits to kill.
2. Second Smg could/should be your explosive guy who can/should also use sneaky shit. The pretty much best smg in the game is PDW, an explosive smg, found in the Massacre site. Also doesn't need crits and will just obliterate everything, no need for a boost from reviving, from SadoMas and whatever. Just use Explodomaniac bg, and Varang Blood, strictly as boost in the early game. Once you get your hands on both a Ripper and a PDW, all Varangian Bloods will never proc, as none of your guys will die, unless you kill them, and you shouldn't, you won't need the crits. In the early game you sneaky shit + rocket launcher as an opening on SJ, but very soon you will dump the RL. Also don't use Vengeful Bond, as a side note, it's honestly too much work, and as you'll see you don't need it. Pets will gimp you by standing in the way of torrent strikes and Vengeful Bond 100% crit chance is noob bait. Everything in this game dies to a white torrent strike from an optimized SMG guy.
3. At least one brawler. In a few scripted fights when you don't get to go first or you screw up, this guy will bail you. Brawlers are so good, you should probably run two of them, if anything for simplicity sake, for utility and ofc, sheer killing power. Lethal Weapon or Mopey Poet. I used to use Mopey for power but now use Lethal for RP value. Both work. Varangian Blood for sure, he will bail you out, when shit goes south with 1AP crits all day. Save the glass knucks from the start of the game for 0.5 combat speed, and dip 5 into melee for striking distance and another 0.5 c.speed. Get power gauntlets early from la perla and he will murder shit. Use concussion bell to just go around and stun everything. 20% strike distance is fine, 25 is better, but never 34. He needs 1AP to attack so it's a huge waste. He wears a full suit of Exoskeleton Armor for like +40% melee damage and he just hilariously punches shit to oblivion.
4. Rattler user, also your mechanic, small arms gun. Rattler is shit when you look at it, and available immediately on the Market of C.S. 4-5 damage x10. This x10 thing makes gamebreakingly op ofcourse. You can use a cryolinkage on this guy, but to keep things thematically use an plasma linkage, a shortened barrel on it and this guy will one shot scorpitrons on SJ with an Unload from the Rattler, try it. This guy benefits most from Weird Science, and the perk for energy damage that increases PER bullet, the more the target has armor. That's why this guy can one shot a Scorpitron.

As I said, all of the above is gross overkill, but just to point you in the right direction. I don't use SadoM. at all, and I (now) rarely use all the "correct" quirks or bgrounds now, just to keep myself not completely bored.

As for other guns categories, Sniper Rifles can't chain sneaky shit, when you attack, combat will start and you'll be down your attacking AP. It can chain ambush like I wrote before, but do that to entertain myself, it's not optimal. The whole sniper rifle category does less than half the damage fully optimized compared to a semi optimized Ripper guy, to one guy, as opposed to the whole room, and for twice the AP cost to attack. Honestly, Snipers are for flavour and RP, not a powergaming build by any stretch of the imagination.

Big Guns are strong, specifically Miniguns, with Incendiary Linkages and appropriate perks like the one from the Toaster and Weird Science fire damage. They are strong mostly for their Torrent Strikes. While Lucia would make a great BG user, I don't like to spend the bullets, so I make her into something suboptimal.

Honestly, you can pick two of the builds from the above and you can RP rest, destroying the game, or do whatever. For companions these days, I just use them as leader rally stations, rez machines with Foam Fingers, usually pointing to my brawlers (or now one bladed guy for RP), to save bullets and not overkill so much.

Still a ripper with 38mm scope and a shortened or a titanium barrel will kill 6 mobs for only 10 bullets in torrent strike, so that's def a bargain.

Before I forget, every one of those guys above, use Threat Intelligences, it's just too good to pass up.