I have no experience with Bitrix, but I have worked extensively with both HubSpot CRM as well as Salesforce.
HubSpot CRM is free, looks great and it’s pretty easy to set up and use. I’ve trained users coming over from Salesforce and they all agreed it was a breath of fresh air. All those day-to-day things are just a lot easier than in Salesforce: contact data is very neatly presented, calls and emails are tracked and listed on the contact record, deals are easy to keep track of, etc.
Don’t get me wrong: you can do all of these things in Salesforce, too, but they usually take some setting up and adjusting before it looks and works the way you want it to.
But that, right there, is the strength of Salesforce: you can get it it conform to pretty much any business process you have. HubSpot CRM is pretty straightforward, which is great for most small businesses. But if you want to start adding products and projects and such, or have multiple sales processes going on at the same time… it gets a little harder to keep track of all of that. Salesforce, on the other hand, is designed for such complicated processes.
At the end of the day, it comes down to what you need as a company. If you need a solid way to keep track of customers, follow up with leads and report on deal progress, go with HubSpot CRM.
If you have a more complicated sales process or have a larger organisation, HubSpot CRM most likely will be too limited for you
Keep in mind that unless you have Salesforce knowledge, you absolutely should be investing in a decent agency to help you set it up and maintain it for you. Or you should hire someone as a permanent admin. The reason for this is that, because Salesforce is so vast and flexible, it can also be really easy to make a mess of it. I’ve seen several older instances that were just beyond saving.
My two cents!
I first answered this question on Quora: