I am in the exact same boat, trying to decide which to buy. I have already bought LP+ and ADW (Both are very outdated and not getting updated) so I am trying to decide which of these two to buy.
Here is the thing, Samsung wants to shove S-Voice down your throat and has disabled access to Voice Search directly. I am rooted on my Verizon GS3, and still can't find a way to directly add a shortcut to Voice Search. Even when you go to the market and look at Voice Search, you do not have the option to open the app, its not in the app tray, and you can not create a shortcut to it to put on your desktop.
Nova Launcher has a built in Voice Search shortcut in Nova actions, making it easy to add to the desktop and restoring Voice Search functionality to the SG3 w/o having to use SVoice as a front end. I am aware you can switch SVoice to use Voice Search (Google) instead of Samsung's Voice Search engine (Vlingo) but you still have to use Svoices front end which is bloated and slow.
I emailed the Apex team (screen shots, etc) and got a blown off response basically one sentence telling me to add the suggestion to their feature request website where people vote on if they want the option or not. Fk that, screw you. Its not a "feature" to have a shortcut to Voice Search built into your home replacement, its basic functionality. What, you cant take the time to send something other then a canned email reply? Thats ok, I will use something else.
When you hit the phones menu button in Apex it has a giant list of crap that comes up (Add, Wallpaper, Theme Settings, Manage Apps, Manage Screens, Apex Settings, System Settings, Lock Desktop, Help). Seriously? Do you need to shortcut all of that from the menu button? Am I going to be switching my desktop theme so much that that option should have an shortcut come up every time I hit menu; can't it just go under Apex Settings?
Nova has "Wallpaper" "Manage Apps" Nova Settings" and "System Settings". Nice and simple, just like it should be when you hit the menu button on your phone from the homepage. Being that you can drag an app icon and hover over the trash to uninstall, I would argue "Lock Desktop" would be far more valuable menu button shortcut then "Manage Apps", but at least its not a huge list of crap I don't need shortcutted from the menu button like in Apex. There is a Lock Desktop option but its buried in Nova settings instead.
Apex however has a cleaner settings menu, with what looks to be more setting options then Nova. I am only comparing free to free as I have yet to decide which paid version I want to buy, but at this point after getting blown off by Apex support, seeing the bloated Apex menu button, and Apex not having Voice Search support built in, I am probably going with Nova.
My personal opinion is Apex might be a little bit ahead of Nova but it seems like its starting to get bloated too which is why I no longer use "Go" products (Launcher, SMS, etc).