You do realize that the user community is primarily other users? And, you're posting around a holiday time. I have a question in about WMWare Player, and haven't had any answer yet. I'm not shilling for VMWare....
The truth is, I haven't ever had to (or wanted to) purchase a legacy operating system, so without that need, I haven't had the "positive experience" you're looking for. There may be discussion boards not in any way related to VMWare or Parallels where one could ask about the same subject with answers already there. But, I did successfully install Windows 7 on Fusion 3 on a MacBook Pro in 2010 and still use it in Fusion 6 on the same Mac. I just purchased Window 7 OS, I think at Best Buy, when I got the Mac. And that was completely a "positive experience". It just wasn't legacy at the time.
To speak about this user community: I've helped and also benefited from other postings in this community about the transition into the Mavericks operating system, which introduced its own set of issues. Back when Lion was released, running Fusion 3 resulted in a black screen. I posted about that, shared a workaround I found, all of this back in August, 2011 on a thread a Mac OS X Lion - Black Screen of Death - Mac Book Pro. I share this to give an example of the support users can and will share with each other in this community, as likely it won't be of much help today.
As for purchasing Windows 7 today (together with a valid license): I can only reply along the lines of "If I were to do that, I would try..." and, having previously purchased from Tiger Direct, would consider them together with outfits like PC Warehouse and similar stores, possibly favoring those that have a Mac counterpart. Local to me near Albany, NY, I have a computer repair shop that I would approach with a request (they would offer to install it for me), and you may have similar places nearby that are local to you.
If given a choice to put Windows 7 or Windows 8 on a VM, I would opt for 7.
