I guess it depends on the area of the country you live in. For example, we used, and still do in rec leagues throughout the area, ASA/USA Rawlings 11" softballs at those ages. However, depending upon the rec league, some don't allow composites at all, some only allow them at 10U and above and others around here don't care.LXT is significantly superior to the Vendetta in terms of performance. HOWEVER...
...The OP is asking about a 29" -12 bat. This is a small and young player (8U or possibly a small 10U). If it's rec league, they are probably using soft compression (RIF) balls, which pretty much negates performance differences between the bats.
Pick the one that your DD likes the feel and look of best.
I guess it depends on the area of the country you live in. For example, we used, and still do in rec leagues throughout the area, ASA/USA Rawlings 11" softballs at those ages. However, depending upon the rec league, some don't allow composites at all, some only allow them at 10U and above and others around here don't care.