I'd like to freeze strawberries for winter, I read online that a method is to sprinkle sugar on them and put into a zip-lock or plastic bag or an air-tight container. another method is to make ice cubes with them. I wonder what the cons and pros of each method is and if one is preferred over the other. and do you know any other methods? I also read about strawberries in simple syrup but I don't like the idea.
Okay. You don't want them to lose their shape or flavor when thawed. I don't know of any way that is possible. Fruits that contain a lot of water are going to be mushy when thawed. No matter how you do it. No exceptions.
The only suggestion I have for you is to maybe dehdrydate them for future use and then they can be rehydrated. That's not a great solution, just an option.
You will want to freeze them as quickly as possible to prevent large ice crystals from forming in the cells. Let them sit in the refrigerator for several hours so they get really cold, then put them in a disposable cooler with some dry ice for an hour or so. Male sure to put the lid of the cooler on loosely to prevent explosion. When completely frozen, move them to a pre-chilled storage container and place in the lower back of the freezer.