You ask a tough question and I'll I'll attempt to answer you. Modern stamps, stamps in general, are generally a bad investment if your looking for monetary gains. Now that's not saying that there aren't investment grade stamps, however they are usually prohibitively expensive and certainly out of the reach of the regular hobbyist and is really a gamble on any sort of return as the market fluctuates so rapidly. Usually it is recommended that one should collect stamps for fun and not expect any sort of profit as far as money goes. I can't speak for others, but I personally have spent more on my "little collection" than I would ever hope to get in return for it should I ever decide to sell it. In my opinion the modern issues
(1950-present) are probably most valuable as postage -There are exceptions but not many. I'm sure someone will chime in and correct me but in general collector grade stamps are just that -for collectors. If you have big bucks you can contact Stanley Gibbons or any of the big stamp brokers for whats called investment grade material but chances are if you have that kind of money you don't need to invest in anything to begin with. I hope this helps you out some?
The Washington Franklin issues is a great area to collect and study. I know that they have kept me out of trouble for long time! lol You really need a good reference book or site to identify them correctly, most of them anyway. Here is what I use and I suppose many of us do - is the 1847usa webpage. -
http://www.1847usa.com/washfrankmain.htmHappy collecting and Merry Christmas! -Jeff