I would go Honda as they are, by far, more common as a brand than any other. A lot of the parts are interchangeable not only between years and iterations of a model, but often between models as well.
You don't say where you are but in my personal experience living in The Bowels of Phetchabun Province, more common replaceable parts such as chains, lights, indicators and so on are more likely to be actually held in stock in the local mechanics workshop. Especially for Honda Waves, as there are substantially more of those (and their predecessors) than anything else.
However, out of my nearest two towns - Bueang Sam Pan (16km south) and Nong Phai (12km north) only Nong Phai has motorcycle dealerships: Honda and Yamaha. (BSP has Nissan, Toyota, Hino, and Kubota dealerships).
The biggest plus, however, is almost EVERY 13 year-old boy, mechanic, or backyard bloke with a set of spanners, knows how to work on Hondas - especially Waves and Clicks.
My Landlady bought a Honda Scoopy-i when she returned from Hong Kong in 2007. Still going and gets a roadworthy no worries (okay, the speedo cable seems to have given up the ghost about four years ago but considering it's only used in the village and the once-a year ride to Nong Phai, who cares?) She is considering buying another next year.
I haven't rued my purchase at all. I wanted a bike with gears so I bought a the top-specced Honda Wave-i 110cc with mag wheels, discs, and electric start. Landlady's daughter learned to ride on it, too, and often borrowed it to ride to school (12km north) on days I was on a driving holiday or overseas. She actually bought her daughter a Wave last year, as well, when she turned 15. She pootles around Phetchabun City where she now goes to school, and rides the 90km each way home for the weekend.
None of them have missed a beat.
Only real "expense" has been a new battery after four years, and two new tyres at around 15,000 (before last wet season) - and many new inner tubes.
A normal, 4000km service is so cheap that I've forgotten how much.
Considering I only pootle around the village to the market / 7-Eleven 3km each way on it (I have a car for anything requiring me to go on the main road) I didn't even service it annually. BUT for my last service (it needed a mandatory registration roadworthy check as it was over five years old) at 17,600km, they also gave it some other bits and pieces - it also needed the scheduled chain replacement and I think that cost an extra 800 baht. All in, I think it cost around 1700-1800 baht, including the rego fee. A normal service is usually (maybe?) 300-400.
Or, after warranty has expired, just give it to your local "mechanic" for the oil change every 4,000 kays and a replacement chain every 20,000. Just remember an annual roadworthy test (which is basically a service with a checklist) is required for road registration after a bike hits five - although some of the Frankenstein's Monsters I see blasting around here with four schoolboys on it wouldn't pass an emissions test, let alone a roadworthy. LOL
Good luck.