But if your budget is absolutely maxed out? Don't fear the eMMC 5.1. Just don't expect it to fly.
emmc-5-1-storage-explained
If you buy an eMMC 5.1 laptop, buy the 128GB version, not the 64GB version. The larger capacity chips are physically faster due to how flash memory works (parallelism again). Do you have a device with eMMC 5.1? Are you surviving or thriving? Let me know in the comments below. emmc 5.1 storage