Which of these HARDDRIVES??

Everyone is likely to have a different opinion as to which brand, depending on past experience.
Most have a 3-5 year warranty and usually last well past that time.
I have been using WD for the last 10 years and have only replaced them when needing a larger capacity drive, others swear by Seagate which are also very good, I have no experience with Samsung, but they seem to be popular now.
You say 250 GB is way too much for you, I can remember when I upgraded from a 20MB to a 147MB and thought it would last me forever, now I have usb sticks that hold a lot more then that and about 1.5TB of internal drive space. About half of this space is used up already.
Go for the biggest you can afford now, the few dollars extra spent will be worth it in the long run, you never know what you may want to put on it later.
Home movies, photos, music, maybe recorded tv shows later on, all these are capable of using space at a fast rate, high defenition recording can use up space at an alarming rate.

I second the samsung f3. just spent 80 bucks (dirt cheap) on a samsung f3 1 terabyte. Super fast. as a matter of fact google it and you will see.