I have an old Second Chance level II - That's a heavy SOB with my big-ole 8" x 12" K30 trauma plate and is not very comfortable. That said, Second Chance has come a long way since I got my vest from them, and they are producing some remarkably light (and remarkably expensive) stuff.
I also have a like-new 1995 Safariland IIIa that my roommate gave to me. Someone gave it to him, and the department he works for now issued him a new vest, so he gave me the Safariland. It's pretty nice and much more comfortable than my older Second Chance. I thought it was a II at first until I pulled out the panels and read the labels.
If you have the money and want the absolute best, go with a top-of-the-line Second Chance. You can't really beat them. If you can, get one custom fitted, because there's no real one-size-fits-all vest that'll be truly comfortable. But then again, you're looking for something for home defense rather than everyday wear.
In the end, Erick pretty much summed it up with "Any vest is a good vest when you need it." I guess my best advice would be to get the best vest you can afford. Anything from Second Chance, Point Blank, American Body Armor, Galls, etc should be just fine and dandy for your purpose.
As far as how to get a vest that is generally restricted to LEO, do a search on eBay (
http://search.ebay.com/search/searc...t=1&SortProperty=MetaEndSort&query=body+armor).