Backup a Samsung phone before switching to Nexus? I used to backup my phone through Kies. Now I'm switching to Nexus5, and I guess Kies won't work anymore to get my stuff back to phone. What should I do?

Also, I know that some data is automatically stored by Google and associated with my account, so as soon as I login with my new phone it should get it back to me. What is this data?

I could also backup my files by hand, but I would like not to lose apps and app data. Thank you!
There are many application backup programs available in PlayStore.


A very light weight application - Super Backup
ES File Explorer
If you are rooted then - Titanium Backup


Plus the data stored by google will be automatically retrieved by google once you login to nexus.