First things first I suggest you change the topic to Something else. Don'tuse your name as the subject no body will know what it's about and only someone who is a bit curious will respond to this thread. Change it to something like Corolla 121 Vs Tiida vs N16 or something
Next out of the 3 cars you mentioned
121's are the most overpriced,abused,tampered cars in the country and are decades old. It's supposed to do good on fuel but with a really old car that has been abused to death , the odo reset half a dozen times and has had more users than a budget-friendly prostitute from Dehiwala ,fuel figures will vary.
The Tiida's the newest out of the lot - if you're ok with the looks it ain't a half bad car. my bro had one for 2-3 years and it was a decent ride. there are quite a few brand-new imported ones around and if you get hand on one i think it's a good deal.
in my opinion Tiida>Sunny>121