What would the best remote access software option be for me when the most important is to keep control over files and chatting?

I need a remote access software that gives me complete control over files and where I can conveniently chat with the programmer while he works with my Excel file.

I use TeamViewer now, but I am hesitating to continue to use it because I might need it for commercial use later, and if I choose TeamViewer now, it might be harder to switch to another later on. If I use TeamViewer for commercial use, the drawbacks are the high price and not good options for upgrading:

https://forums.anandtech.com/threads/looking-for-alternatives-to-teamviewer.2261483/page-2

Some alternatives seem to be ScreenConnect, GoToManage, etc.:

http://www.toptenreviews.com/software/utilities/best-remote-pc-access-software/
http://www.businessnewsdaily.com/9448-best-remote-access-software.html

It seems I can make TeamViewer very safe (and also deny file transfer) with the advanced options:

https://www.howtogeek.com/257376/how-to-lock-down-teamviewer-for-more-secure-remote-access/

Connection speed is not the top priority, but being able to chat at the same time as someone is working remotely with an Excel on my computer while this Excel can't be transfered is the top priority.