Right now, we are in a bear market that has lasted for close to 8 months. No one knows for sure how long more it'll last. It also depends on your risk appetite, and whether or not losing that $500 will make an impact on your life.
- For a safer route, I'd recommend BTC. In such a market, it'd be a gamble to purchase any altcoins. Your best bet would still be BTC. However, of course, don't expect any insane gains.
- For a riskier route, I'd recommend you try out masternodes. There are a ton of masternode coins available, you can find them on
masternodes.online. Most of the new coins provide insane ROI and would be good for quick flips. However, due to the low liquidity of many not so well known masternode coins, the fluctuations in price can be quite scary. If that $500 means the world to you, I wouldn't recommend this choice.
I agree on the first part of this recommendation, but not the second part. Too many masternodes around and they are all tanking and most of them will probably die.
As an alternative to BTC I would chose some good altcoin which has lost a lot in this bear market, like Ethereum or Waves or Neo.