As of blogging this now. I think the most profitable virtual currency to mine is Ethereum. Although Ethereum is new, but appears to be somewhat active, not really active but enough to have some kind of momentum going.
Bitcoins SHA256 and Scrypts Asics are no longer profitable to mine, even if you have free power, well someone have to pay for power and hardware. The so call ASIC immune coins to mine with GPU all of them, not profitable. Even if Bitcoin were to go up $500.
So who’s mining these virtual coins now a day? yes, just commercial miner, big farm with massive equipment hard to mine these virtual coins. Only a handful of people individual miner are still mining for fun, not for profit.
Ethereum appears to be a little bit different than other virtual currencies coins when it come to mining. Ethereum, you can mine with all equipment, that included CPU, GPU and ASIC. However the algo appear to be a memory eater, meaning it uses a lot memory. The memory I’m talking about is the GPU memory, not so much with computer RAM although it would help but not significant. Therefore it’s only for GPU mining, useless to mine with ASIC and CPU as we would not get much hash rate out of asic and cpu.
In term of profitability? it’s the best as of now.