This study tackles the issue of Alzheimer's disease diagnosis with electroencephalography based on the quantification of the brain functional connectivity. In this work, we evaluated two measures of functional connectivity, namely Phase Synchrony largely used in the literature and Epoch-based entropy, to distinguish between Mild Alzheimer's disease patients (AD patients) and patients with Subjective Cognitive Impairment (SCI subjects). A Linear Discriminate Analysis was used to discriminate the two groups of subjects with a leave-one-out procedure. The obtained results indicated that the accuracy reached 98.33% with Epoch-based entropy and 52.33% with Phase synchrony in θ band