I saw my share of ambrose, but never garner, so the comparison lacks meaning.How young are you? Did you watch Ambrose much? Garner was great but Ambrose was next level. Garner was never the best bowler in the side either, whereas Ambrose was almost constantly the best bowler in his side.
To be clear, I'm not arguing garner is better. I just think its a question worth asking.
Being the best bowler in the side is an understandable reason for ranking ambrose ahead, but it isn't a logical one. There is a gulf in quality between Marshall and Walsh.