That's certainly true, mate. Bitcoin is and will always be the best cryptocurrency in the world. The large hashrate (miners) backing it, and developers working on it says it all. Bitcoin Cash is simply a copy of the original cryptocurrency which started this craze. It's important to know that a copy will never replace the original project no matter what its efforts will be. BCH enjoys of a decent price and market cap because it carries the "Bitcoin" brand/name. If it wasn't by that, BCH wouldn't have been in the top ranks in market cap. Whenever it's a good investment or not, it's up to you to decide. But know this, Bitcoin Cash has been a subject of controversy ever since it came into inception back in 2017. That's largely because BCH depends on large block sizes for scalability which in effect, centralizes the whole Blockchain. It may be extremely convenient as digital cash for day-to-day purchases, but not as a store of value. Given that Bitcoin Cash has higher node requirements (higher bandwidth and higher storage capacity) than Bitcoin (BTC), it has suffered from a lower hashrate making it vulnerable against 51% attacks.
If BCH's hashrate goes lower, it could experience the same events as Ethereum Classic (ETC). Which is why, I recommend that you choose Bitcoin (BTC) above anything else for the sake of your investment. As I've said earlier, the decision lies in yourself. Always do your own research before making a decision based on other's opinion. If you do that, you'll be successful in this wild and crazy world of crypto. Just my opinion