"Better" for what? Does this question have real-world applications for you, or is it simply rhetorical? And, are they costing you the same? Are they in identical condition?
LX (now known as SLX) was considered the bottom end of Shimano's upper-end mountain components (LX,XT,XTR), while Alivio was/is near the bottom, just above Acera (IIRC).
Personally, everything else being equal, I'd go with these LX units over the Alivios. If there's a price or condition disparity, then obviously, that changes things, but without more info, nobody can tell you much more than "LX was higher up than Alivio".