I recommend Windows 7 as well, but really it just comes down to personal preference.
In Windows 8 you have to deal with the hassle of moving between the desktop and the "tile" interface. Most people find that annoying - in fact, MS got such bad reviews about Windows 8 that it actually laid off 15% of it's workforce. Hence why now they're aggressively offering free upgrades to Windows 10.
Ultimately their biggest mistake was turning Windows 8 into a "one size fits all" OS that could be used for both regular PCs and tablets. They should've split them into 2 OSs, but they didn't.
That's why they included the tile interface in Windows 8, to keep tablet users happy and using Windows - a colossal blunder on MS's part.
However, some people like the tile interface as it gives them some built in apps for news feeds and other fun web based googahs.
Also, if you're going to get Windows 8 I'd recommend getting 8.1 instead - Start menu is absent in Windows 8.
For work purposes, I'd say that Windows 8 may have too much of a learning curve - especially if you have to record something (which it sounds like you do) or have to take incoming phone calls over a phone network, so your best bet might be to go with Windows 7.
But ultimately it's personal preference. I'd recommend finding someone who has a Windows 8 PC and just spending time playing around with it - or go a store and play around with it there if you can.