Pick whatever relationship database you'll actually use, from spreadsheet to CRM to whiteboard, and drop anything you don't.
Ask 10 people on a New York street for the best slice in Manhattan and you'll get 10 right answers. Relationship databases work the same way. A spreadsheet, Salesforce, a purpose-built CRM, even a whiteboard or a pile of business cards on a desk (I have watched both work for people). The test is one question: will I use it? Forget what your colleague uses or what someone praised in a Facebook thread. Habits stick when the task is easy relative to the reward, so the best tool is the one that returns the most for the effort you'll really put in.
Before committing, ask:
Whatever you successfully start using is fine. If you're not successfully using it, drop it like a too-hot coffee with no sleeve.
When we were selling Contactually, people flocked to it thinking it would cure their networking woes. Many set it up in a flurry and never signed in again. They, and we, mistook the tool for the solution. It took me years and millions in lost revenue to learn that a tool only works inside a system: strategy, then tactics, then tools. Otherwise it's the expensive treadmill in a friend's basement that became a clothes rack.