What is the best portable laptop should i buy? 14.1 or 15.4? best brand? to be bought ASAP! UK and worldwide ?

I'm no computer expert, but i have a sony vaio and it's awful. It's the worst thing i ever bought, been nothing but trouble since i bought it. Anyone who uses my laptop is shocked by the poor performance. To be fair though, i've been told that this is one of Sony's worst laptops, and i may have just been unlucky with it but i'd still be very wary of buying another sony vaio.