Both WD and seagate have a good track record, seagate 7200.11 had some problems, but is now sorted out in 7200.12. However, people still consider WD to be more reliable. So go for WD Blue which I suppose has 5 year warranty. Seagate has 5 years warranty.
All HDDs are similarly priced and the cost per GB is around Rs. 4.20 for 500 GB ones Rs. 3.40 for 1 TB ones, quite value for money. I'd say don't buy anything below 500 GB, they are much less vfm at cost per GB over Rs. 6