Ask HN: Best development language to launch a product in

I'm a non-technical entrepreneur and have previously launched a successful start-up and am working on a new company currently.

The product is going to be web based but is also going to have to interface with the financial industry and able to pull and interpret a good amount of data and metrics.

Not knowing much about the technical side, I was wondering what tips and languages would be recommended to look at as a starting point? I've been told both Rails and Python as two to look into and wanted people's thoughts. Thanks.