HPE MSA (modular smart array), formerly HP StorageWorks MSA, is a series of storage appliances, from Hewlett-Packard Enterprise, a product line built for a modest budget, available as the HPE MSA 2052 hybrid flash array, the HPE MSA 2500 SAN storage appliance, and the MSA 1050 SAN storage.
The dual controller configuration of the HPE MSA trumps the Synology DiskStation's single controller configuration. For that alone, I would select the HPE MSA. Without that setup, any controller issue or firmware upgrade is disruptive to the systems the SAN is providing storage …
The MSA is much cheaper than a Nimble. Spinning disk storage is much cheaper than flash storage. Just know that you are going to get what you pay for. The MSA doesn't stand up to what the Nimble can do, but at the same time, it works really well in disaster recovery scenarios.
We had tried Dell's solution but found it to be similar in price to HP and with very poor support and some performance issues. We also compared with some other vendors but ended up choosing HP due to reputation and wide user base.