Should not the emphasis be on Dewi Lingo? "Dewi Lingo ydy fy hoff chwaraewr rygbi." (Yes, I guess it depends on the question!)
As you say, it depends on the focus of your question - is it 'Dewi Lingo' (as opposed to, say, Hefin Lingo), or is it 'my favourite rugby player' )as opposed to 'my favourite cricketer')?
Either answer is accepted here.