I am using this Seagate Slim portable 500GB external Hard drive for around 2 years. From that only I am not getting any problem till now. It’s a good external hard drive and its of light weight and also it’s very slim. It is very wasy to carry in laptop bag too.
Now coming to the performance, at first I got around 25mbps transfer speed, but now it’s reduces to around 15mbps, but its not bad enough. I think Seagate is better than WD hard drive.