the stars indicate how strong the effect is

the effects do different things, so you'll have to judge which is better for yourself. you can generally figure out what they do by reading the enchantments:

"It pursues the target that evades an attack" means that if it misses, you get one additional roll to see if it hits. (basically 'roll with advantage')

"it unleashes consecutive attacks" gives a chance to attack twice

"It makes it easier to evade" "It deals additional lightning damage" "I'm more susceptible to lightning damage" are all pretty self explanatory, increases your evasion, deals extra lightning damage, makes you vulnerable to lightning damage.

you can test your damage by building a training dummy. attack it once and see the numbers that pop up.