If you are stuck between choosing company instead of specs I would say Dell, anytime Dell. Even if it may cost about 5K INR more or less depending on specifications.
My experience of comparison between these three tells me:
- Dell is more flexible with qualities like cross compatibility between batteries of different models (like Latitude and Inspiron have same battery), standard charger port so you can share charger of same electrical specifications. HP and Lenovo have their own custom shaped port.
Analogy: Android with micro-USB which majority had and iPhone 5s with lightning connector which was rare in 2013.
Dell is more robust. Drop your HP and Lenovo and they will break like ceramic. I have seen both Dell and Lenovo fall. Screen connector of Lenovo broke and the person was forced to to painstakingly use the crippled laptop for another year somehow due to financial issues, as service center could not help and asked for a large sum to change body. Dell survived without a scratch.
It is fairly obvious that HP is overpricing their products & accessories (HP battery costs about 6-7K INR, Dell battery costs around 2-3K INR) and with the reliability being not commensurate to the price. Dell is reasonably priced and gives most punch for the price.
Dell Support is simply amazing. The person sitting behind that toll free help number knows almost everything and gets you out of any situation.
Almost all Dell laptops can be customized. I myself could upgrade from 4GB to 8GB RAM.
The performance is simply amazing. I run heavy softwares like MATLAB and Xilinx as well as high-end games like Battlefield 3 and Mafia II smoothly (Core i7 3632qm coupled with 2GB AMD Radeon HD 7730). The Full HD screen is beautiful & sharp and brings out the best quality that the media has to offer.
If you want to force me in telling you issues with Dell I would only speak about battery life. It has reduced from 2.5-3 hours to 1-1.5 hours in 3 years of use. Happens to all laptops though.
UPDATE: A lot has changed since I wrote this answer and I made sure some points were updated as of Jan 2016. Dell however, still stays the best!* item