It's nice to see a Toyota fan on this forum after all.
If you consider about fuel economy the best you have here is 121 and vios. Even though Vitz, Yaris and Belta has comparatively smaller engines , they are not as good as those two on fuel. Specially these two are felt underpowered when you climb hill roads (won't matter if you're planning to drive them on Colombo city limits)
Comfort - Allion and 121 are much comfortable than the others. Allion has better front and rear leg space than 121.
Design- it's quite personnel. For me out of these allion 240 looks better than the others. Vios, Vitz.belta and Yaris look stupid to me
All these cars are reliable, but if you're planning to use it for another 5 or more years , it would be wise to buy a comparatively new one