picnic vs previa(01-05)

Your question is very general. Let's be specific on a few things:
1. Fuel consumption - Previs is more expensive in using gas. Check other Yahoo.knowledge on the actual fuel consumption if wanted.
2. Inner space - Previa is bigger and easier to access, especially for the last row of seats.
3. Function & features - Previa has more choice and more fun. Picnic in general is rather primitive.
4. Driving & control - Picnic is easier to control, especially when you try to park in those MK or TST carparks.
5. Price - Obvious and no need to mention.

I personnally like larger car and Previa is preferred. This is subjective though.

previa is good