As Davy, I too am biased towards the Lancer. But it doesn’t mean that we insist on omitting every other option and going for a Lancer every time this kind of a thread pops up. But looking at the list of cars you have put up, it seems the best car for you would be the Lancer CS3.
Since I've spoken about pros and cons of CS Lancers in many previous threads I believe listing them all again is pointless at the moment. However, I'd like to point out few facts that I observe in the car models stated in your list.
1.Mitsubishi Lancer CS3 manual 2011/2012
I've rarely seen CS3s with manual boxes that have been manufactured in these years. Most of the cars that were for sale had automatic CVT transmission. One of my friends had a manual one but bugger sold it to be cut for an Evo conversion.
CS3s with manual transmission are one of the most fun cars I've driven in this segment. The best part with the manual Lancers is that the clutch is very soft and smooth. Anyhow finding a manual car made after 2010 would be very difficult IMO. The down side of the CVT is that if it’s not properly maintained, it would cause issues. And if that happens, you are in bit of a trouble cuz finding a recon CVT box will be difficult as JDM of CS came with a 4 speed auto box.
By these years almost all of the cars were bought and used by companies rather than individuals. The car being a brand new import and being a 12 year old model made it pointless for an individual to buy it for that price at that time. So, if you are going for a car that were manufactured in the years you've stated, you have to consider this fact as well. Nothing wrong with company used cars as long as they've been used properly and carry all service records (this is a long shot though). Mine was a company used one and it was pristine when I bought it.
Last year I saw several CS3s in the marked which had done over 150k kms, one car had 205k on the clock. So be mindful about the mileage. Also few months back, Unit#d Mot#rs too sold some units that were used by their staff.
Other than these, the ride quality, handling, power, ground clearance, leg space in the cabin and durability of this car is best in its class IMHO.
Lastly finding parts for a Lancer around Badulla area would be difficult when compared to a Toyota.
2.Toyota 121 Manual 1500CC 2003
This is fairly an old car. But a solid one. The most concerning part about this car is that finding well maintained genuine car. Since these are goon on fuel, most cars by now should have been to the moon and back. These cars were very popular with cab companies before Axio’s and Hybrids took over.
So if you are going for this, you’d have to be very careful.
3.Toyota Yaris 1300CC 2008
No driving experience with this car, however I’ve been a passenger several times. It’s not specious. I don’t like how it looks. Whether this car is powerful enough to be used in hill country is a question you have to consider about.
4.Toyota Vios 2005
No experience at all. AFIK this is not a Japanese made car. Wonder what happened to these cars as I seldom see a one in Colombo nowadays. Back in the day these were very popular. This was the car for people who could not afford an Allion 240.
Since this is not a JDM you might have to think about availability of spares. However I remember there was a regular member who spoke very fondly of Vios in general.
5.Mazda Axela 2003
If a car could compete with the Lancer CS3, this would be it. The only downside is that the car is now bit old. I remember some weird issue with these cars where flies get stuck inside the rear tail laps. There was a thread about it also if I remember right. Again Im unable to comment much as I haven’t used this car.
One of the best cars which I believe might suits you that is not there in the list is the Honda Civic ES8. Please consider that one as well. One of my cousins had an ES8 RS manual, absolute fun to drive car. That’s a Ripper if you could find a one. Even an auto is superb. The car pulls like a train.
Hope this (plus all the input given by the other members) helps to make you the correct decision.
Best of Luck