One of the CB650 variants would be the obvious choice. I don't know why but they have a great sound even compared to other 4 cylinder bikes. A bit heavy though...
If you like the looks the new XSR900 has had brilliant reviews. I know it's a triple but I have the MT09 (same engine) and you still get that lovely howl from the top end with the added benefit of loads of torque down low. I know it's above your ideal cc but it's lighter than the Honda 650 range and has rider modes so there is really no drawback to the larger engine. It also has the up/down quickshifter. Yamaha Kaset Nawamin (Riders club) have been good to me in terms of servicing. Even when I threw it down the road there was no issues with spares and it was back to me within a few days. If they finally release an R9 with sensible ergonomics (i.e. sporty-ish but not supersporty) then I'll seriously consider one to replace my 899. I think that 120-140hp is really the sweet spot for the road.
You could also consider a Triumph Trident if you're prepared to consider a triple. They are quite physically small though... If you can wait a few months a fully faired version is coming and it looks pretty relaxed ergonomically. Kind of like an upright, chilled Daytona.
https://www.cycleworld.com/motorcycle-news/triumph-daytona-660-spy-shots/
I also considered the ZX4R but I couldn't really think where I'd use it.
In my opinion Ducati, Honda, Triumph, Yamaha and Kawasaki are the best in terms of dealerships in Thailand (especially if you are in Bangkok) although Ducati obviously don't make an inline 4 and the V4's are quite spendy.