RocketReach provides real-time verified data for 450 million professionals across 17 million companies, worldwide.
RocketReach is very user friendly, and generally their data is high quality. We like that it marks personal emails so you can assess whether it is appropriate to contact that person there.
TaskDrive supports sales and marketing teams by providing personalized lead research, data enrichment and account-based insights.
If you need a very high-touch list building service then this one's for you. You get assigned a researcher who allocates 40 hours/week just to you.