Best for: People who like PvE or like to Co-op.
Best Weapon: Ludwig's Holy Sword
Best Consumable: Oil Urn (Doubles fire damage)
Best Spell: Choir Bell
For boss fights, their are a few with high elemental resistances (Martyr Logarius), but the vast majority of enemies in the game have some elemental weakness that can be exploited. Not to mention their are a plethora of cheesing tactics including using the Flamesprayer against Rom, spamming Executioner's Gloves (often on a weakspot that is hard to reach with melee), and MOST importantly Oil Urn + charged Ludwig's against almost any boss in the game (oil urns double fire damage). The last one literally wrecks everything, although it's tougher to do against some bosses than others. Additionally, higher discovery means that Chalice Dungeon crawling will give you higher returns on your investment.
In PvP, the Arcane Build suffers but not as much as people think. The oil urn + Ludwig's Sword is still a viable tactic, though much harder to do. Oil urns or any thrown consumable can (believe it or not) hit if you don't lock on (important!) and throw it onto the ground near the enemy since it has a fairly generous AoE splash range. It still has a long wind up, but with the right timing and opportunity you can land them with practice. Charged attacks, however, will be less effective than regular sword swings due to it's potential to be parried and the sheer speed increase and unpredictability of PvP over PvE. But HP isn't as high as a boss so it's not really necessary. Even regular swings have the potential to OHKO an opponent depending on level, stats, and gems.
In Co-op, Choir Bell is extremely good theoretically. The indicates that their is no limit on distance, so you can heal your nearly dead buddy on the other side of the map because he decided he had to kill those stupid worms for no apparent reason even though they give you hardly any blood echoes or an invader got to him before you did. This also is fairly affordable despite it's 10 QSB usage because you can use blood echoes beforehand which automatically gets healed back after you use the bell.
Best for: People who like to screw around in PvP. People who like MGS, Deus Ex, and other fun sneaking games.
Best Consumable: Blue Elixer
Best Spell: Messanger's Gift, Hunter's Bone for running away
Best Weapon: Mercy Blade or Reiterpillasche for very quick charged back attacks.
Best Stat: Skill. Needed to increase visceral attack damage so you can OHKO your opponent after a charged backstab.
Best Attire: Anything dark to blend in since Blue Elixer only makes you transparent, or heck just go naked.
Now this is an interesting build. This is a real and legitimate build and not just for laughs. This may even be viable in PvE if you carefully use Blue Elixer against the opponents that have a higher detection ability (werewolves for example almost always detect you without a blue elixer regardless of how slow you approach them). Obviously bosses are a different story, especially if you decide to nerf your vitality, but at least you don't have to worry about gems too much. Plus, you my as well use all the cheesing tactics you know of because let's face it, if your doing this build your not about honor anyhow haha.
Best for: Anybody who likes to invade in PvE or look like a katana weilding, gun slinging badass. Anybody that's dreamed of being a cowboy. Anybody who simply likes guns.
Best Weapon: Evelyn, Chicage, Reiterpallasch
Best Consumable: Bone Marrow Ash (triples LH weapon damage)
Best Spell: Beast Roar
This needs no introduction as this is one of the most popular builds in the game and it's not hard to see why. It has a bonus of being extremely powerful and looking badass at the same time. This may not be the strongest in PvE build in the game, but with Bone Marrow Ash it's quite good, and for PvP it's easily one of the best.
Of particular note here is that the Reiterpallasch which is actually more powerful than the Evelyn not including Bone Marrow Ash. The reason being is that it can be buffed and fully gemmed, while an Evelyn can not. The difference is quite drastic and can be around a 250 - 300 difference in damage per shot.
Bloodtinge builds may consider investing into a skill/bloodtinge build as well, if you prefer to have melee damage along with your gun/transformed katana damage but might have to sacrifice in other other areas.
Bass Cannon Builds
Best for: People who like PvP and blow their opponent away in one mighty shot. Not much else to say really.
Best weapon: Varies, depending on style. Ludwigs Sword, Kirkhammer, and Logarius' Wheel are usually the most popular
Best Consumable: Lead Elixer, Beast Pellets
Best Spell: Messenger's Gift
One of the most satisfying builds in the game no doubt. Their is nothing like seeing your opponent getting blown away by a cannon shot. There are several build for Bass Cannon, they are Str/Arc, pure Strength, Str/Bl, and quality builds. Obviously, the main ingredient for this build is Strength as that is what's needed to wield the mighty Bass Cannon. If you like to invade and this is a great build, and is great in PvE as well. Strength weapons usually have a staggering effect that stunlocks most big enemies that smaller weapons don't do. And then the cannon is great for doing massive amount of damage on a weakspot.
Best for: People who love to play aggressively.
Best weapon: Varies. Blades of Mercy, Reiterpillasch, Burial Blade, Threaded Cane.
Best Consumable: Lead Elixer, Beast Pellets
Best Spell: Hunter's Bone
Those being the pure skill (BoM, Reiterpillasch) and hybrid skill (Burial Blade, BoM). These are without question your aggressive builds. The Blade of Mercy are one of the favorite weapons on this Reddit and has one of the best movesets in the game. It's a pretty straightforward build however. The one thing that is important to mention is that it's been discovered that visceral attack damage scales with the skill stat, so a skill build can be fairly versatile, they can be aggressive with BoM's while playing for the parry (kind of defensively) with the Reiterpillasch a moment later. Threaded cane is handy as well for range and AoE when fighting bosses and mobs.
Here's some info you need to know about which are not mentioned above. Saw Blade, Cleaver, and probably more; These are fantastic weapons and by no means do I intend to give them the slight. They tend to be all-around weapons however and can be used in almost all builds as they don't have a lot that makes them unique. Another honorable mention here is the Reiterpallasch as it's low bloodtinge requirement, and the lower damage of guns in the first place means that almost all builds can benefit from this weapon even if they didn't invest a lot into bloodtinge or skill. It's ability to be gemmed means that it's one of the highest damaging guns in the game.
Credits: Special thanks to Hussary for making this build guide for Bloodborne.