This article aims to summarize my take on the sustainably of BCH and BTC + LN.
BCH - In its current evolution offers a better user experience due to low transaction fees, simplicity, and strong app development but at the cost of losing decentralization and sustainability in the long term. The solution for BCH to scale is to have unlimited block sizes. If every single transaction in the world no matter how little was on the blockchain this would quickly grow to a size that would be too large for home user hardware to run a full node. Every node needs to continuously validate the data and sync it to the current block height. Supporting 50,000 transactions a minute at an average of 250 bytes a transaction would equate to 6.57 terabytes of blockchain growth a year and 32 terabytes every 5 years. If all blocks were full at the current bch blocksize of 32 MB only half the time you'd have 8 terabytes of growth annually. One of the most exciting new applications of electronic cash is micropayment in games and applications like read.cash. Micropayments could greatly increase the number of total transactions that need to process. Yes, BCH is friendly to users who lack technical understandings, but in the long run, it is not viable.
Bitcoin - Scaling philosophy of keeping the blocksize small so affordable home hardware can run a full node, this democratized access to underdeveloped parts of the world and makes a government taking down of the network near impossible. Initiatives such as Taproot also help to batch transactions and make blocks more efficient. The block size, fees, and wait times of the main blockchain are influenced by the cost of the lowest common denominator of common computing hardware. Computing hardware is not evolving as fast as the demand for BTC so fees inevitably start to rise to balance out the system and layer two solutions such as the lightning network emerged to fill the need in the system for a fast payment solution with low fees.
Lightning Network - Offer a true payment scaling solution that preserves the democratization of node ownership and is built as a payment layer on top of the main Bitcoin blockchain. Once within the LN network, users can send and receive bitcoin instantly, at a minimal fee, with no limit on transactions per second, and with basic hardware. Currently, with LN you would do all your daily transactions under $1,500 within the lighting network and only use the main BTC blockchain for larger transactions or on/off-ramping to fiat or LN. LN also assist in privacy as you can transact between nodes in the network millions of time for years and none of the transaction data is saved except for the most recent state of the channel. Channels can also be run privately on TOR with true anonymity.
In conclusion- I see BTC + LN as the best option for a global P2P payment system. time will tell.
Hope you found this helpful.