I Have 2 Seagates, and use one as my TimeMachine Backup
As stated in the title, I do use Seagate externals. I have a GoFlex, which I use strictly as my TimeMachine backup drive, I manually back-up my Mac (about once a week, maybe less if I'm being lazy). I also have an older Seagate that I reformatted and partitioned, so that I can use half for my Windows files and the other for my Mac. I haven't had any problems, and found that even for a novice it is easy to find tutorials that allow you to manipulate the drives for your purposes. I did the partitioning so long ago that I'd have to go back and read how I did it, so trust me, I'm far from a techie. Bottom line, I like the size, the ease of use, and the reliability they have provided me, so I would recommend them. Good luck to you!