This is simpler than it looks...

Points to note:

• 1.0.x is stable 
• 1.0.x has many extensions
• A beginner may have a lot of trouble migrating 1.0.x to 1.5.x
• 1.5.x is the future
  

Summary : If you can find your required extensions have been released as 1.5 NATIVE, then definitely go with 1.5.x . Remember 1.5 NATIVE versions are appearing for the main extensions pretty quickly.