I'd stick with Windows 8.1 as Windows 10 is merely a tech preview. It may contain bugs and isn't even a finalized product. 8.1 will be more stable and supported by more applications (I suppose)
If you have a spare drive and want to try it out go for it. I put it on one of my old drives and thought it was alright but I wouldnt use it as a primary OS at this point.