DisplayFusion

The free version does NOT include the taskbar on multiple screens option. Because of that, I'll be uninstalling this and installing an alternative such as ZBar.

Displayfusion and Actual Window Manager are the best display-based productivity software I found. They both support the following (indicating who is the winner in each category)
Multiple taskbars (Actual Window Manager)
Multiple Wallpapers (Display Fusion)
Titlebar Buttons (AWM by a small margin)
Window snapping (DF by a small margin)
Screensavers (N/A)

I personally like DF better because it has a little bit more configurability and the wallpaper manager is a bit better. The taskbar is better in AWM but it doesn't prove to be a deal winner for me.

The triggers is my favorite feature, they rock! I can control window placement for apps exactly as I see fit. You too will love this software if you have multiple monitors!

It's one of the best multimonitor application that I've found. Main feature that I use in DF is monitor splitting feature. This works perfectly with my huge 42" 4k monitor. So basicly I split my desktop to four separated virtual desktops. I have tested out many other apps but DF seems to be best for my workflow!

And one of the best thing that it's available from Steam!!!

[Edited by Niittymaa, March 20]

I have been using this for years. I love this program! It has so many options that I am sure that I have not explored the half of them. I am REALLY happy about the send to option that allows you to simply click a button on the page title bar and it will send it to the second monitor in multi-monitor systems. No need to exit full screen mode to move a window now. It also gives you the ability to select the power user menu from your cursor position which is quite handy. On top of this, all updates are included when you purchase the program.