How to choose tools for web dashboard? I am working in a small sales company. Started with making relatively easy, small, static reports in Excel, but then it was required to make a lot of highly-customizable and adaptable reports, that are really troublesome to do in Excel. I do a lot of VBA, but that still doesn't meet my needs. Our ERP has no BI solution. Excel can't keep up with amount of data used (millions of lines). 

I am only accustomed to JS and HTML and have some experience working with 
relational databases (MySQL, MariaDB in particular).

Basically, what I need help with is deciding what tools would be appropriate for my  needs considering I am not in a rush and would like to develop some skills along the way. 

I would like to create a dashboard that would retrieve data from a local DB and process it. I would also need the dashboard to be dynamic - be able to change some inputs and run calculations accordingly. I am interested in packages that are suitable for mathematical analysis. Reports would include both tables and graphs.

I've read about R and Python packages, but still am not sure which one would be the most appropriate.

In the future I guess I would like to distribute it to other colleagues (run it from a server; have different accounts with different access level etc.).

Will highly appreciate any tips!
There are quite a few tools that serve this purpose (E.g.: Tableau , QlikView are expensive but feature rich; Kibana / Dash have Open Source versions).

You can start with Kibana. It will take a week to learn it. Advantages are :


Part of ElasticSearch stack, it is easy to ingest data (Say that you need to update data from ERP every hour / day /week etc.)  'Logstash' component isused for ingesting / updating data
Widely used, so tutorials / documentation are easy to look up
You can customize dashboards with JS / html
As usage grows, you can add features (Such as access control, periodic email of reports as PDF / Excel etc) 


Some tutorials / Documentation  :

https://en.wikipedia.org/wiki/Kibana 
https://www.elastic.co/products/kibana

https://www.youtube.com/watch?v=gQ1c1uILyKI