I was actually toying with this myself for my Lizardfolk Kensei.
Str 10
Dex 16
Con 16
Int 10
Wis 16
Cha 8
This is at lvl 6 mind you.
I think regardless of which you want to start off in, you want to stick with it for the first 5 levels. Get that Extra attack.
I have longsword, throwing knives, and now a longbow as my Kensei weapons, and so far it has been pretty fun. When I am on a roll I can quickly reduce a sizable chunk from enemies, if not out right drop them in a round.
You certainly have a sizable list of options that compete for your bonus action, and Ki points as well.
I would say you either want to end up choosing armored or not. And really that is up to you. My vision for a Ronin for instance is one that isn't armored.
So you would want to choose a fighting style from Fighter that compliments that. Depending on preference that could be Archery, Dueling, Great weapon fighting, maybe even Two weapon fighting. Though that last one is going to be more taxing on your bonus action.
My opinion then is, level up to 5th in whichever class you want first. This will likely decide your method of calculating your AC. At that, your build is starting to take shape at 8th level.
From there you can likely take whichever level you think thematically fits. Keeping in mind there are definite jumps in power to most classes at 5th, 11th, and 17th. Starting in fighter, allows you a quick bump from the ability/feat choice at lvl6, while monk 6 is deft strikes for Kensei and an additional weapon choice, not to mention attacks counting as magic for overcoming resistance.