Which phone is better? sony xperia SP vs lumia 920 and sony xperia L vs lumia 720.?

Whats your purpose with these phones? You are comparing 2 different OS here. 920 and 720 can be upgraded to WP8 and has very user friendly interface but os customization is limited, just like iOS. The way the contacts are integrated with social networks on WP8 is a breeze to use and works great out of box.

Android on the other hand is more for a pro/techie user who knows what they are doing with it. I own SP and a lumia 1020 myself and both are good phones in terms of hardware,build quality and design. 920 is like a younger brother to 1020, so enjoys the same qualities mentioned above. Battery life is better on 920 than SP and same with 720 vs xperia L. Dont just compare the specs and choose a device blindly because there's lot of factors to consider in between. Go to a multi-brand showroom and spend some time with these devices to see which one suits you.