Best engine for towing - 5.3 or 6.0?

On paper the 6.0 makes more torque, which is what towing uses:

Engine	Size	Years	Power	Torque	Compression	Block	AFM
LM7	5.3 L	1999–2007	270–295 hp	315–335 lb-ft	9.49:1	iron	No
LMG	5.3 L	2007–2014	315–320 hp	335–340 lb-ft	9.60:1	iron	Yes
LQ4	6.0 L	1999–2008	300–335 hp	355–375 lb-ft	9.40:1	iron	No
LQ9	6.0 L	2002–2007	345 hp	380 lb-ft	10.00:1	iron	No
LY6	6.0 L	2007–2013	361 hp	385 lb-ft	9.60:1	iron	No

Speedway's generalization: Stock 5.3 is rated around 320 hp / 340 lb-ft; stock 6.0 around 300 hp / 360 lb-ft, depending on version and year (Speedway generalization). We don't have a source comparing them in towing, so the ratings are the fair comparison.