Re: reliability, you might want to read this:http://www.behardware.com/articles/810-6/components-returns-rates.html
It is a bit old though.
If you can, go with a SSD, your productivity will be better.
The value of raid-1 and it's variants like raid-5 is that you can recover from a drive failure quickly. It is for servers that can not tolerate any interruption.
Modern hard drives have a advertised mean time to failure on the order of 500,000+ hours. That is something like 50 years.
With raid-1 you are protecting yourself from specifically a hard drive failure. Not from other failures such as viruses, operator error,
malware, fire, theft, etc.
For that, you need external backup. If you have external backup, you do not need raid-1