One way to measure language difficulty in the Romance languages would be to look at verb tenses and compare their difficulty across the family.
Let us take a look:
Most difficult: Italian and European Spanish (generally 6 endings, though American Spanish only has 4-5).
Average difficulty: French is simplified from a morphological point of view compared to European Spanish and Italian: it has 3-4 endings for each verb tense. Furthermore, plurals are not pronounced except when liaison is required.
Easiest: Standard Brazilian Portuguese makes use of just 2-3 different endings for every verb tense.
