Best (and easy to use) Launcher for Nexus 5

I use Nova Launcher Prime on my Nexus 5. The free version of Apex offers more customization than the free version of Nova. However, Nova Launcher just feels more polished. Go with Nova Launcher Prime.
 
I would say Action Launcher is the best. Not only is it extremely customisable like Nova and Apex, it also uses an innovative new layout.

That said, I still prefer the Google Now Launcher with some root tweaks.
 
I wish Nova would get swipe right to Google Now. I really like that feature and prefer it over a google now tiled widget. Other than that, Nova is my choice.
 
If you like the Google Now Launcher but want a little more customization, Blur is a nice new launcher.

My personal favorites are Atom, which I'm using right now, Action, Themer, and Nova. I'd say Themer and Atom are the easiest to customize.
 
I use Go Launcher Ex. I used the free version for a few years and then paid for the full version when it went on sale a while back.