Best way to resize images?

[Fennec]

Looking for the best way to resize an avatar for a website that won't result in any loss of quality (if possible). 

So far from playing around I've found 3 ways to do this.

a.) Drag and drop the image into GIMP > Image > Scale Image > Set Width & Height. (This makes the image look blurry even though I'm only reducing it by 50 pixels wide and 100 pixels tall. 

b.) Drag and drop the image into GIMP > Image > Canvas Size > Set Width & Height > Use the move tool in the canvas size window to move the image around until I've found the right spot > Click Resize. This looks much better than a.)

c.) New > Set Width & Height > Drag & Drop Image > Use Move Tool To Reposition Image. Looks clearer than a.) as well. 

So is option b.) and c.) the best way to do this absent loosing any image detail? 

Thanks.

Maybe some kinda sharpen filter will make images look cleaner / sharper afterward?