Watchful, vigilant, wide-awake, alert are comparable when they mean on the lookout especially for danger or for opportunities.
Watchful is the general word.
Vigilant implies keen, courageous, often wary, watchfulness.
Wide-awake stresses keen awareness, more often of opportunities and relevant developments than of dangers.
Alert stresses readiness or promptness in apprehending and meeting a danger, an opportunity, or an emergency.