I’ve had both QNAP and Synology NASes and find Synology’s software easier to use, especially if you are just getting started. The DS218+ has a pretty good CPU as mentioned above. For Seagate NAS drives go with the Iron Wolf. I have used Red and Iron Wolf and haven’t had issues with either.
Before you dump a load of money into hardware that will eventually fail you should consider storing your media in the Cloud. G Suite for Business for $10/€8/£6.60 per month gives you unlimited storage on Google Drive (the alleged 1TB limit for <5 users has never been enforced). Then let Google worry about hardware failures, backups, management etc You can just mount up your Google Drive on your Plex server as though it were local storage using rclone or similar. If you have a need for remote access then consider renting a VPS & put all your resources out in the Cloud.
Both Synology and QNAP have a “Live Demo” you can use. Give them both a try and learn your way around. See with feels the most comfortable to you and how you think. Ease of use is just, if not more, important than pure performance.
Everyone, thank you for your advice. I picked the Synology DS218+ with a Seagate ironwolf hard drive. I appreciate you taking your time out to answer the question as I have been doing a lot of research and had a hard time getting a clear answer.
@trumpy81 Thank you for the information and the link to the FAQ. I went through the FAQ in detail and will hopefully be prepared to set up the NAS. If everything goes well, the system will be up and running by Friday night.