U can't compare mehran and joy but sure buy THE joy...
Oh...i had mehran once :S
On a scale of 1-10;
Tell you what, Reliabilty=-1
Spare Parts Availability=10
Salvage Value(after 5 years)=4
Joy might score low on spare parts but if u know there are places where u can get them very cheap.
Simply put, joy has a very low resale value! but it won't give u everyday headaches like mehran.
Hope i have helped u here, Regards