I don't get why so many people on this thread advice against investing, maybe they don't even understand how it works, or had some bad experience. Anyway, the whole point of any investment is to make a small risk and get some reward, and the chances of success must be higher than chances to lose. This is definitely the thing about casino investments, since the house edge is on your side, and you have a huge number or rolls to make that house edge work.
Now, about which site should you choose, you need to make your own research, get some in-depth understanding how casino operate and so on. From my personal experience, I can say that crypto-games is quite reliable, although they already have a huge bankroll, so your 0.2-0.3 BTC might not yield the highest return. They also accept altcoins, which can be a quite interesting option.
Also I have investment at
yolodice, the casino is new and the bankroll is not giant yet, so there's a potential to get a good profit, the also allow to leverage your investment for a higher risk/reward.