What is the best ERP system or any other system for managing a business?

I have worked with OpenERP (now Odoo) since 2009. I was a core contributor at the time as well.

I understand the questions is old, but I'd leave an answer here for anyone who might stumble upon this question.

I would recommend you to consider Tryton - a fork of OpenERP (also Open Source). The project is supported by a not-for-profit foundation (like Mozilla Foundation for Firefox) and is relatively a better quality project in terms of modularity, code base and ease of development.

Happy to assist anyone who is considering an Open Source ERP system for their business.

depending on your business you can also use Waveaccounting. it is a free SaaS app.
I use it and have no affiliation with them.
There are many systems of course you can use but it is also about the size of your company.

The simple answer here is there's no one-size-fits-all ERP solution, and it very much depends on the specifics of your company. There are several major considerations including how large your company is, the degree of complexity of your business, the volume of data, the need for company-wide integration, and the price you are willing to pay for software.

From what you've described, the feature set you need is (1) financial accounts (2) hr management and (3) productivity management. If these are the only three sets of features, you may be better off going for point solutions that specialize in each.

If you have already determined that a point solution is not enough and specifically need integration across the whole company, then take a look at Netsuite. It is widely used for companies that outgrow Quickbooks and need more integration beyond their financials, particularly among the Inc5000 community.

Bottom line: picking an ERP is a very important and tough decision to make. There are hundreds of alternatives on the market and you need to develop a detailed set of requirements and compare several of the main contenders to see which fits your circumstances. You do not want to make a decision and change to another system later, transitions from one system to another are a nightmare.

I am currently working with a company who made the wrong choice. They purchased a product based on the prior experience of an employee, and battled against the complexity of the system for 18 months. It has caused incredible frustration amongst the internal team, and causes lost productivity of >20% across the company. They have had to build their own internal system and are diverting tech resources away from their product to do it.

No-one can really advise you without more detail. Your best bet is to develop a detailed spec list, create a shortlist, and carefully evaluate the main contenders. This is one of those decisions that's important to get right the first time.