While I can't confirm which is easier, I can say that GameMaker requires a 150$ paid license for web support. However, Unity games in-browser tend to be harder on the player; anyone playing the game needs to install Unity web player, while GameMaker uses HTML5, which most browsers support natively.
Viewing post in Web Browser Game | Unity or GameMaker?
Fuuuck $150 for the HTML5 export? I have GameMaker 1.4 Pro but only for Windows and Tizen (For some reason...) export. I originally got it when the base engine was free and pro was half off but now it looks like I made a bad investment.
Well it looks like Unity is my best choice here. Unity web player seems like something most people would download at some point in time. I know I've already got it. Plus it's free to use. Anyway, thanks for the reply!