Based on the calories in
one 10 oz package (3.5 servings @ 30 calories per serving = 105 calories)
compared to the calories in
1 lb fresh (4.5 servings @ 25 calories per serving = 112.5 calories),
one 10 oz frozen is almost exactly equal to 1 lb fresh (trimmed and mushy leaves removed).
Trimming all that raw spinach is time-consuming, but squeezing thawed spinach isn't my favorite activity, either. Plus a good fraction of the frozen-thawed spinach goes down the drain because it sticks to my hands or the colander as I squeeze it.
With fresh spinach: I remove tough stems, blanch it in boiling water for 30 seconds, drain, rinse with cold water to cool, allow to cool some more to get to room temperature, squeeze into a ball - it's much easier to work with than pre-chopped spinach - and then slice the ball and slice the slices to end up with chopped. That's the procedure used in James Peterson's Vegetables cookbook to prepare the spinach for an Indian Vegetable Stew and in my opinion the result has better flavor than thawed frozen.