Depends on what you want.
Warpriest is a little more hit stuff-y and Inquisitor has a little more teamwork-y/magic-y stuff, and some spells that aren't on the cleric/oracle list. For Two-Weapon-Fighting in particular, neither are great because your going to need to spend 2 swift actions (IE: two rounds) to fully buff all your stuff. The inquisitor spells are a bit better, but TWF is notoriously feat heavy and war priest gives extra feats every three levels. War priest also has blessings which are either only buff a single weapon, or give an ally a bonus to something, which is great for your flanking buddy like a rouge, or even a tank fighter. War priest also has fervor which is a great healing tool that builds into channel energy so that you can go from healing yourself to healing your party. Inquisitor, however also gets some cool unique stuff, but maybe just a little bit less useful if your primary goal is to hit things and kill them. You have judgements, which are any where from alright to pretty good, though they are yet another swift action to cast and have severely limited use early on. Cunning initiative is great for a TWF build as your sex will already be pretty high, letting you consistently buff your self at the start of combat. Then there is really, my opinion, the most unique part of inquisitor, the ability to use team work feats solo. Not always terribly useful, but just kinda fun, it gives you a new feat list to work from that otherwise goes unused at most tables (unless you have a cavalier). Thumbs up on tengu but check with your DM because its kinda weird to be a giant birb in a city of say elves, or dwarfs, or really anything that isn't mostly other tengu.
I don't know if this analogy will make sense to you, but...
War priest = divine magus (basically)
Inquisitor = divine bard
cleric = divine wizard
oracle = divine sorcerer
fair warning before you build this character, it is hard to land your secondary attacks a higher levels as 3/4 BAB, character, this will be even harder for you because of two weapon fighting.
Wepon Focus Wakizashi
Two Weapon Fighting
(if war priest) Double Slice
(if inquisitor) Dazzling Display
(if war priest) Two Weapon Defense
(if inquisitor) Double Bane
Improved Two Weapon Fighting
Both can do martial
Both can do decent spell casting
In my opinion War priest does the martial aspects a little bit better (better armor, better feat progression, more consistent damage)
and Inquisitor does the magic stuff/burst damage a little bit better (judgement+bane is a force to be recon with but you can only do it like 2x a day, better spell list)
Hopefully this helps. Cheers!
TWF requires lots of feats: Inquisitors do not have nearly enough as Warpriests. Additionally, Inquisitor's Bane applies only to one weapon (by default).
I suggest Half-elf with the Human FCB to get an extra feat every 6 levels and the Arsenal Champlain archetype to get Weapon Training. As per wakizashi proficiency, get Ancestral Arms as alternate racial trait or a cracked opalescent white ioun stone.