Ride wise Platz is good, but when it comes to power and acceleration it lacks somewhere... Bodywise it is heavier, thats why it has a very good road feel and smoother drive.
Platz is very low in re-sale and the demand you mentioned is too high also. It should be around 6.5-7 lacs if the car is in good condition.
Plus one thing more I like to mention you here that you are buying a 2005 model, and definately you will drive it for like 2 years or so... But after that time a 6 year old Platz will have no good buyers and it would be very difficult for you to sale your car. It wont be the case with Vitz though. The choice is yours...
But whatever the condition is, if you ask me, I love Platz