Good CRM to use

There are many CRM brands in the market today. From open-source to commercial ones, there are a plethora of choices. I could not decide which one to select among the choices.

I have heard of an unknown brand, ConvergeHub, which promises lots of features but I had seen from other reviewers that it is not that good due to its high pricing as compared to its more popular competitors, interface is a bit difficult to use and not that user-friendly and most of all the limited features of its mobile apps.

So, can you recommend a good brand of a CRM? Something that is priced cheaply but its features are great and actually useful. A good open-source alternative would also be appreciated so long as it would gonna compete with the commercial ones.