Its hard to say long term. I built my miners not just for the coins, but for the fun of it too. I love computers. When coins are launched, they are not on an exchange so its hard to buy unless you can find private sales. So mining gives you a head start. Mining is also how transactions are confirmed so they are crucial to the whole thing, if you believe in the concept, build a rig and contribute some hashes. If it all goes to sht, you can always build a gaming rig from it all or sell it off at maybe 50% of what you paid.
I guess that means you should mine several coins as a hedge against risk.