Depends. Buying coins now means there's a bigger risk, but also potentially MUCH greater reward. Mining is extremely slow, therefore the risk is much lower but the reward is smaller. Do not forget that currently mining is very profitable because the price surged in the past few months, but soon the profit will decrease dramatically. Because more people will mine, whatever the profit is now, it will halven in 1-2 months.
This short-term thinking is very very poisonous. If one is mining only for exchanging the coins for fiat immediately, this person should not start mining at all. Better throw the rig from the window.
If I start mining ETC right now(I don't care about the DAO, top-dev scam-politico), price will go higher in the next years. So, mining ETC will benefit a lot in the long term.(2-5 Year for me)