I have several different default configurations I use for client builds.
For middle-budget standard home use computers - you know, the browse the Internet, light gaming, check email:
OS: ADATA SP900 64GB
Storage: Seagate 1TB
This comes out to less than $150, usually.
For gamers who need their games on the SSD as well:
OS: Samsung 840 120GB
or for even more space
OS: Crucial M500 240GB
Storage: Seagate 1TB
For high throughput applications, I build with Samsung 840s in RAID. For home storage servers, I use Western Digital Green drives.
I am sure other people have strong opinions on brands, but I mainly use these brands out of habits for certain types of applications. If there are better, there are better, but my clients don't complain.