But Bitcoin has “first-mover” advantage, you can buy almost anything with Bitcoin core. From coffee to apartments and it’s return is much more than Bitcoin cash.
A better idea would be a 70–30% investment in Bitcoin and Bitcoin cash respectively.
Also, if you’ll have Bitcoin then you are eligible for any free currency(like Bitcoin cash) comes out of any Bitcoin fork.
True. Bitcoin Cash may be better in technical aspects, but it's not in terms of long term security and reliability. This is because, it will become centralized over time as blocks are filled beyond the 32mb limit, making it expensive for an average person to operate a full node. However, if technology would somehow grow at a fast pace, and costs would become reduced over time (Moore's Law), then there should be no problem at all as people will be able to afford storage costs in the future.
In the meantime, that's not happening, and BCH would eventually become centralized because of the high storage costs and bandwidth it will require once blocks reach the 32mb limit. Despite this, Bitcoin Cash is ready to scale to a large user base, while maintaining low costs and fast transaction speeds.
In my case, I would prefer Bitcoin over Bitcoin Cash, due to its decentralization and unparalleled security. Even if Bitcoin is slow and expensive right now, it may not be in the future once it successfully adopts the Lightning Network. Once this happens, then it'll be a fierce battle between Bitcoin and Bitcoin Cash to determine which is capable of scaling to many people while maintaining decentralization (which is the most important factor to consider IMO).
Nevertheless, it wouldn't hurt to invest into BCH too, as it could give you a lot of profit if it skyrockets in price within the future. Just my opinion