Totally comes down to your business's needs and personal preferences. I use ActiveCampaign and used Contactually in the past. I use ActiveCampaign even though its CRM is not the best, because the automation features are fantastic and easy to use. It also integrates very smoothly with Wordpress. I prefer to have as much of my information as possible located in one package, rather than having multiple packages talking to each other through complicated Zapier workflows.
I discussed this with @Greg Dickerson in an interview and he uses the basic Microsoft Outlook/Excel suite, and it works well for him. Goes to show that investors at the highest levels just need the tools that work for them, and it doesn't need to be the fanciest, most feature-laden software package out there.
Still others use Podio, which has a truly insane amount of customization options. I don't use it because it was just too much customization for me. I wanted more built-in structure, because I'm not in this business to be a web developer!
In my opinion, the steps to figuring it out should be:
1) Write down the functions and features you want a CRM to have. Then identify your top 5 priorities.
2) Make a list of CRM packages - it's been discussed on BP a number of times, so you can build a list based on that. Hit Google as well
3) Do as many free trials as you can stomach. With many of them you might decide in literally the first 10 seconds they're not the right fit. You'll probably get it narrowed down to two or three. Pick one and commit to it!
If you really commit to it, you can certainly make a decision within 1-2 weeks.