Both are good, if you have already a mining RIG then it worth a lot because if you have reached the ROI then you are earning money like a boss now.
But even though there is a lack of motivation in the mining rig because people are saying that Ethereum is going to be moved to Proof of Stake which stops the mining and people will move to another coin.
Investing in bitcoin also is a good thing because the ethereum price has been increased too much recently, few months the price was ~$50 and now the price is $280
I think if you have the skill, it is better to mine.
It has nothing to do with the skills, being a miner does not need to have a degree or something else, count it as a hobby.
Mining information can be found easily here in forum or even in youtube since ethereum mining has been very trending nowadays.
You still need knowledge about the operating system, video cards etc.
It has never been as easy as it is now; to mine. Try smOS or one of my builds (see my signature); either way: it's significantly simpler than what mining once involved.