I've been tooling around with an idea for a Halfling Brawler with the Snakebite Striker, hope you're not all tired of that one, and taking Halfling Opportunist so he can use the Opportunist ability they get at 11 and the Counterpunch feat to get his Sneak Attack on his AoOs.
My plan is to go Brawler 12 and Opportunist 5, but that still leaves 3 levels to play with. I'm wanting something that gives him a bit more sneak attack, but I'm not sure what exactly to pick. Rogue? Ninja? Assassin?
I'm wondering if anyone has any advice on what would be the best idea, and I'd also like some suggestions on how to arrange his levels.
There is a halfling trait called helpful and the bodyguard feat that are worth grabbing. Helpful increases aid another to grant a +4 on ally's attack or AC, and body guard let's you give this AC bonus to adjacent allies when they are attacked as an AoO. One of the cavalier orders would get this up to +6 within a few levels, which is sweet for a small PC because you can take your mount anywhere a medium person can go and your mount is a valid recipient of aid another.
Not quite in line with what you asked, but as an untyped bonus, since you will probably want Combat Reflexes with your AoO build anyway, it's too useful to pass up for a single feat/trait investment. It also gives you something to do with the high Dex when you are not using those AoOs.
Are you still tooling around with the idea? I'm currently working on a Halfling Opportunist...
What exactly is your question? What is 'best' to you? There's a ton of classes that give sneak attack... we'd need more of a build to see potential synergy between it and the various classes (slayer, alchemist (vivisectionist), unchained rogue, etc.)
Attributes, main weapon of choice (fists?), ... what are your roles besides smashing things hard (and getting their aggro I guess, since you want them to attack you for snakebite, right?
Also have you considered going the non-lethal / enforcer / thug / sap-master route? You can chose to deal non-lethal with fists, right?
3 levels of unchained rogue gets you dex to hit and to damage and 2d6 of sneak, so you could start with that if you're dex based, then go from there (brawler/opportunist as you planned). I see an intimidating dude with wirey muscles bounce through the room and pow in'ya face until they beg for their mamma to come save'em...
If that's interesting to you, you should check the details on that again...
Did I mention Snake Fang -- also kinda nice. Small dip in Master of Many styles monk can get this. not bad when you're sneak attacking on any AoO...