Go and test drive them all and others that are in the price range too. Buy a car/topcar magazine to check what's all in you price range. You are the person that has to live with the car.
Test drive them properly, many people don't put them through their paces. Put the radio off and the aircon on as you like it. Set your seat and mirrors and get comfortable. If the fuel light is on tell the salesman to throw in gas and then to shhh while you drive. Take them on the freeway. Accelerate hard, eg 80 to 140 and feel if it's reasonable in various gears, imagine having to overtake a long truck. Is the car comfortable at 120, is it quiet enough, are the revs low enough, are you comfortable, is there something left in the engine to overtake. Feel where the torque is in the engine by pulling from 1000rpm in 3rd to the rev limiter taking note of where in the rev range the car starts pulling and where it slacks off, does the spread of the torque suit you? Emergency lane change at 120, really sharply(swerve), does the car slide all over the place and need correction, or is it composed? Could you avoid a cow/pedestrian wondering onto the freeway? Brake hard from freeway speeds, is this acceptable? If you can find a hill take note of how much throttle and gear you need to use. Drive over some rough road and some speed bumps if possible, is there enough cosseting? Find some corners that you can take spiritly to test how the car behaves. Take note of the weighting and feedback of the steering and pedals during your drive, as well as the ease and acuracy of the gear selector movements. Whats visibility like? Can you see everything out the back with the mirrors. Can you see enough of the edge of the car to confidently judge parallel parking. Once you back, then only check out all the ancillaries such as radio, bluetooth, etc. Check if there is enough leg room at the back with the drivers seat set in your driving position and if there is enough boot space.
Walk into the service department and ask what the major, minor, cambelt and brakes services cost for the model you are interested in.
Of the 4 you mention,
I haven't driven the i10 Grand.
The regular i10 and and the picanto I've driven and found them to both be borderline unstable when changing direction quickly at freeway speeds. The i10 Grand should be more sure footed due to its wider track and increased wheelbase. The picanto's interior was the best in class I felt, but the waiting list was extremely long. The Sandero is a Dacia, not a Renault, stay away. The vivo drives solidly but is barebones, even sound deadening is thinned out and its sluggish with that 1.4 in the big body.
- its a bigger car, what I'd rather go for just on the size point of view mostly
