Hello there everyone!
This fix will make controls in Accel World vs. Sword Art Online as close to the Lost Song's as possible.
Firstly, let me state this clearly - this isn't the ideal solution. And there never will be before Bandai Namco will wake up and ask the company they hired to port this game to PC to fix it (99% that they won't do this ever). Me and some of the people I know even decompressed both games files and tried to analyze it with goal in mind to migrate Lost Song's controls to AWvsSAO, but without any success.
Secondly, this is keybindings that is comfortable for me (I've played like that almost 200 hours in Lost Song), so it possibly could not suit you.
Important notice: for using this fix like it was conceived you should have a gaming mouse with at least two additional buttons on the side.
So, link... I mean lets start!

You need to download this .ini file ( https://drive.google.com/file/d/1DjAWmXisLqe-2Mp8snZimWBvV1qaF8Uk/view?usp=sharing ) (copy and paste it in your browser) and place it in your Accel World vs. Sword Art Online folder.
Location of this folder:

[your main disk, where your system is installed]:\Users\[your username]\AppData\Local\Accel World vs. Sword Art Online

For example, this is my path to this folder:

C:\Users\DEADSnAke\AppData\Local\Accel World vs. Sword Art Online

In some cases you won't see AppData/Local folders, so if you can't, use this official guide to make them appear: https://support.microsoft.com/en-us/help/14201/windows-show-hidden-files

When you will change the original file to this one, your controls will be like that:

[W]/[A]/[S]/[D] - move forward, left, backward, right.
Hold [Shift] (while moving) - sprint.
LMB - weak attack.
Additional MB1 (4th in the order) - strong attack.
[F]/Additional MB2 (5th in the order) - evade (while moving), block (while holding Shift), start flying (after long holding), speak to someone/use something (when staying near it).
[Space] - jump.
Holding [Shift] + [1]/[2]/[3]/[4]/LMB/Additional MB (4th in order) - activate pallete number 1 and use skills in it.
Holding [R] + [1]/[2]/[3]/[4]/LMB/Additional MB (4th in order) - activate pallete number 1 and use skills in it.
Fast pressing on [Shift] + [E] - switch from one character to another.
[1] - start flying.
[2]/[3] - open wings/soar in the sky after flying.
[4] - close wings.
[T] - change pallete from skills to items. Hold [Shift] and press [1]/[2]/[3]/[4]/LMB/Additional MB (4th in order) to use according items
[E] - lock on target. Use Mouse Wheel Up/Down to change aiming on enemies/body parts of bosses.
[Z]/press Mouse Wheel - open command/items use menu. [1]\[4] to switch between commands and items submenus, [F] to use and [E] to choose commands/items you need. Press [Z]/Mouse Wheel again to close.
[Esc] - open/close menu.

That's all for keybindings. Now let's move to...

Firsly, little explanation. You can't change mouselook from RMB to anything else, so you can't really use strong attack on right mouse button. There is a variant, where you can use it for strong attacks, but can't control camera by mouse at all.. For me (and, I think, for most part of other PC gamers) looking around by mouse is very important thing for comfort playing. So let's do this!

For this you need to install additional app named AutoHotKey. You can download it on the official site: https://www.autohotkey.com/

When downloaded and installed it, download this file ( https://drive.google.com/open?id=1Em9nUCLNwWYc6mku6fuVmorlrbGxmMjn ) (copy and paste it in your browser) and place it on your desktop. After that before launching the game click twice on the AWvsSAO.ahk and run it.

AND NOW DO NOT CLICK RMB BEFORE YOU LAUNCH AWvsSAO!

When the game will start, press "Continue" or "New game" and when you will see your character and will be able control him\her - press RMB once. Woala! Now you can control your camera without holding RMB pressed all the time.

What you can't do:

- You won't be able to go back in the game menus by pressing RMB
- Don't switch with Alt-Tab to Windows, it will stop all the magic from working

What you can do:

- You still can press RMB in game, so don't worry about pressing it occasionally, it will do nothing
- You STILL CAN use Steam overlay/chat like always, just without RMB-functionality.

How to close this: after you will end playing game and get back to desktop, run Task Manager (Ctrl-Alt-Delete), and find AutoHotkey.exe in the Processes tab, than close it. And after that press RMB anywhere once. Congrats, you are back to normal!

So, that's all! Now you can spend hundreds of hours in AWvsSAO on PC as a proud member of PC-master race, just as I did before. Wait, I just created it and haven't used this fix on my first playthrough, when I was playing with centering camera all the time... Whatever.

If it was useful for you, then my job wasn't for nothing.

And if you need any help in any of SAO games (with walkthrough, bugs, leveling up, multiplayer, etc.) feel free to add me and ask for help. Sometimes I won't be able to help, but if I could, it will be my pleasure.

Good luck and have fun!