Stealth classes

[Shadowscale]

I was wondering if someone could elaborate to me what each stealth class's niche and strengths lie?
I'm very curious in:
Rogue
Rogue (unchained)
Ninja
Inquisitor
Investigator
Vigilante
Slayer

I apologize for all the questions and the depth of the task of anyone is up for elaborating at all.

[Sayt]

There isn't so much a niche as a hiearchy. Alchemist and investigator has alchemize invisibility.

Ninja has access to invisible blade and greater IB, for second.

Rogue (and possibly slayer by extention) gets dampen presence+counts as SF (Stealth) as a rogue talent for an honourable mention for easier Hellcat stealth access.

If you don't have invisibility, you need Hellcat stealth or hide in plain sight, otherwise you just don't get to try (unless you have a lenient gm)

Edit: Whoops, misunderstood your post!

Slayer is a beat-stick, but a sneaky, cunning beat-stick.

The ninja is a sneaky striker. They can do big single target damage, but they're restricted by the ki pool and by the d8 hit die, so protracted fights and long days don't suit as well.

The inquisitor is more of a split face/skillmonkey/strike than a strealth class, IMHO.

The investigator is a hardcore skill monkey that gives away some combat prowess, but gets alchemy.

The rogue... I think is probably the weakest of the bunch, and mostly exists as a legacy class. Unchained supposedly gave it some love but I haven't looked into that enough to comment.

[Extra Anchovies]

The main counter to stealthy characters is stuff that Invisibility doesn't help against. The main annoyances are blindsight, blindsense, tremorsense, and scent. In 3.5 we could just nab Darkstalker, but it's a bit harder to get around those abilities in PF. Blindsight and blindsense can be worked around with Dampen Presence (http://www.d20pfsrd.com/feats/general-feats/dampen-presence), which easily accessible for most characters. Scent is taken care of by the Negate Aroma (http://www.d20pfsrd.com/magic/all-spells/n/negate-aroma) spell, and as a 1st-level spell is fairly inexpensive in a continuous item. Shame it's not on the Sor/Wiz list, or Rogues could get it with Major Magic. Tremorsense can be dealt with by flying, convincing your DM to let you make Horseshoes of a Zephyr for non-horses, or possibly Spider Climb, depending on how you define "ground".

Anyways, on to the classes.

The Rogue and Ninja have a number of useful talents and tricks, which can be taken by either of the two classes:
Camouflage - higher bonus than Skill Focus (Stealth) until level 10, but not useful in cities or dungeons
Dampen Presence - stealth functions against Blindsight/Blindsense, covers Hellcat Stealth's feat prerequisite
Eerie Disappearance - moving into cover or concealment can make observers lose track of your location, and you get a free demoralize attempt against anyone nearby
Fast Stealth - no penalty to stealth for moving at full speed, which is a must for effective sneaking
Vanishing Trick - it's short-duration, but as a spell-like it doesn't have any verbal or somatic components, so you can renew it without breaking stealth
Wall Climber - could work to negate tremorsense, depending on the rules definition of "ground"

Inquisitor is very nice. The Heretic archetype gets +Wis to stealth, the Inquisitor spell list has both Invisibility and Silence, the Trickery (Ambush) domain gets on-demand concealment for a small but still useful number of rounds each day, and the Heresy inquisition gets to roll twice on Bluff, Diplomacy, or Stealth a few times per day.

Investigator can get a free +1d6 to all Stealth checks with the Unconventional Inspiration talent, and their formula list has Invisibility and Negate Aroma. Extracts (like potions) can be consumed without breaking stealth, which is nice for pre-combat buffing. They also have limited access to rogue talents, including camouflage and fast stealth.

Slayers can get Camouflage and Fast Stealth, and their studied target bonus applies to Stealth from 7th level. The Stygian Slayer archetype gets an Invisibility SLA, and instead of applying studied target to Stealth they get to use scrolls and wands of 0th to 4th level sor/wiz Illusions (plus a few other shadow-related spells). Other than that they don't really have any unique options.

The Stalker-spec Vigilante has rogue talent access and can get no-strings Hide in Plain Sight at 8th level, so they've got a solid array of options. There's also a spec-generic talent that gives the benefits of Fast Stealth, along with the eventual ability to ignore difficult terrain. The Psychometrist archetype doesn't replace the normal specialization options, and opens up easy access to useful stuff like minute/level invisibility from Illusion and flight from Transmutation.

Of those, I think Psychometrist Stalker-spec Vigilante might actually be the best at sneaking around, but it takes a lot of investment on its part to get there. Investigator and Inquisitor both have plenty of tools in their boxes other than stealth, and uRogue and Ninja can get solid stealth abilities with ease; the Slayer kinda struggles next to the others, but can still put up decent stealth numbers without giving up their combat prowess.

[avr]

I think that given Paizo's myriad options it's more useful to consider 'how can I get ability X?' than to try and map 'what abilities can these classes give me?' Also, if that's meant to be a list of all the stealthy classes it's missing a few, starting with ranger, and once you start including those myriad options, druid, sorcerer, wizard, fighter...

BTW, I often prefer to use alchemy (http://www.archivesofnethys.com/EquipmentMiscDisplay.aspx?ItemName=Deodorizing%20a gent%20(vial)) to defeat scent rather than a spell like negate aroma.

[Pyromancer999]

The Cipher is an Investigator Archetype that's pretty Stealth-focused. Gets a lot of good stuff like Stealth Bonuses, Hide in Plain Sight, and even an ability where people have to make a Perception check to know that you're even there. There's a couple more things, but can't remember them off the top of my head.