Getting an MHO means points, and that the asker appreciated your view. But for old questions, an MHO is just randomly picked, so not all MHOs are equal.
Likes on the other hand show how many other people appreciate what you said.
While I like being picked as MHO (especially if by the asker), I like likes more. They better represent whether people in general like my opinion. They also suggest more whether my opinion has even been read or not. No likes, and I wonder whether anyone even saw what I wrote. Several likes, and I feel happier, because, hey! people saw, read, and liked my opinion!
MHO without a doubt. Sure it's great to have people agree with you but it's even better when you have the best answer/opinion not to mention the points that come along with it.
The only time when getting likes is better I would say is when the QA refuses to listen to you or anyone and the votes show all the people that support what you have to say,. It's the best and closest thing hire going to get because you're sure as hell won't be getting MH.
Honestly, for me it's likes. The more I'm liked (or unliked back when we had the feature), the more it means that people put their brains in to use and were made to think because of what I wrote. That makes my day.
likes, because mho is so dependent on how much someone else likes your answer and not necessarily how good your answer is. like, someone could ask for our favorite color and give mho for some dude saying poop