tbh I prefer morgana a million times over lux because her shield is a point and click + cc protection, and her Q has better scalings. And her Q snares for 1 second longer at level 5
you have to take a risk if you want to ult with morg, lux only got safe dmg, morg shield only shield from ap and it's single target, lux shields the whole team, lux got more aoe and dmg in general
they're both good in the right matchup, don't compare them
lux can spam more and man.. speaking of that, compare the shield cooldowns. lux shield keeps your team healthy, was up against a teemo and ashe last game, shrooms and ashe w became nonexistent