Not being secure is not fair to holders/users of coins.
So hashing power is very important.
For that reason classics like IXCoin,
DeVCoin, I0Coin,
GRouPcoin, CoiLedCoin and GeistGeld look good, in order of how long a term you need to be looking at.
All of them except IXCoin and maybe DeVCoin have had periods during which no public merged mining pools included them in their merge, thus were excellent for miners; anyone could merged mine them easily at one time or another. Plus having been around for years anyone who wanted to has had plenty of time to pick them up cheap.
The last two are still not mined by any of the large public merged mining pools so are STILL great opportunities for private merged mining miners.
GRouPcoin is only merged by mmpool.org as far as I know, and I do not know of any exchange that lists them yet, even
Vircurex has not listed them yet though they have said a long time ago that they would so once they see IXCoin and I0Coin do better volumes quite likely they will list them, probably resulting in a lot of dumping by mmpool miners who have been accumulating them for a long time now. Maybe the best time to pick up such coins though could be before they get listed; you might still be able to get them dirt cheap in private deals with miners.
-MarkM-
I agree with this, low hashrates make the coin less secure and less fair for coinholders and why merge mining is such an attractive prospect for the future. I think even dual merge mining with sha256 and scrypt like RibbitRewards uses would be great.
I hold tons of the old coins like ixc, dvc,GG, i0c just from merge mining. I however dont have any coiledcoin but ill definitely look into it. I also dont have any groupcoin but again, something to look into. Thanks for sharing.