besides car price, you need to consider the price for maintanence (change gearbox oil, engine oil, spark plugs), gas consumption and availability of parts in case you need to exchange mechanical parts.
My suggestion is Honda Stream 1.8 (new model). because it's gas saving, powerful, easy and cheap to get parts for maintenance.
If u want slide door for small size of 7 seats car, Mazda 5 seems is the only choice in the market. Picnic or Stream, they don't have slide door. But the interior of M5, personally not prefer.
For M8, you may be surprise that is longer and wider than a Previa.