I believe the Norwegian Forest Cats here in Sweden are quite big. I'd say the average weight on males are 7 kg and on females 5 kg. A few of the studs reach 10 kg.

According to the FIFé standard the Norwegian Forest Cat is a large cat. It doesn't say anything about weight though but the medium sized cats within FIFé weigh 3-5 kg (females on the lower end and males on the higher).

I think you should go for the type you like the most, not after which one is the easiest to show.