They are easier to mine but from what I can tell harder to exchange because you have to go through mtgox. If you have a rig that can mind either btc or ltc I would go with btc.
Was signing up to get in on an auction of ASIC Miner shares but can't post there yet. So far I think Bitcoin is great and I really like all the big names getting on board especially Peter Thiel. If he was able to change online payment with Paypal I think he can do it again with Bitcoin.