Well it depends on what purpose you gonna buy it. And looking at the current developments in the technology market you must be seeing there are varieties of laptops including notebook laptop, Tablet PCs etc, which are being offered by renowned brands like Sony, Toshiba, Dell, HP, Lenovo, Samsung, Acer, and many others. And also there are models available for business users, gaming enthusiasts, students, and home use. But the main thing that concerns while buying a laptop is its ‘system configuration’ which includes the processor type and speed, RAM, hard drive capacity, graphics card, and other accessories.
And finally it is to be decided the purpose behind the purchase that means whether for student college work and other learning purpose, professional / business purpose or mainly entertainment / gaming purpose, while to enjoy better gaming graphics and speed you need to have a processor of 4 or 8 GB for fastest game processing and a graphics card which should have a video memory of 1 or 2 GB, it is a good idea if you choose a bigger screen like one with 17 to 19 inches.
While for a student t is better to go in for a 2.0 GHz processor; as it would be suitable for Internet surfing, email work, and text documentations with RAM capacity around 1 GB or 2 GB for carrying out all the work fast that is required in college projects. It is better if you choose a hard drive of 250 GB capacity.
And if your are at job and you need a personalized laptop then go for a 2.0 GHz processor with 4 GB ram but screen wideness may be a bit less in this case say 15 inches.

Most laptops now days have similar (and adequate tech specs). I would look for build quality of the laptop and the rest is just personal preference. Make sure to go to a store and try out the keyboard and trackpad before buying it.

only one thing i can say, dont worry about the brand, worry about the inside. processor, ram,hard drive space etc.