I'd give a nod to Sony and Corel at http://www.amazon.com/Video-Editing-Digital-Music-Software/b?ie=UTF8&node=567572
That said I find many new to video editors blow up over encoding issues. That is, since there never was a strict standard for video encoding I find myself transcoding at times using Handbrake and VLC Player to get the content into the editor.
Another common complaint is that it's slow. The newer folk to editing will ask which editor is faster. Some even blow up when the answer is given.
So, I have just about realized that movie maker isn't going to suffice for professional videos, however, I am not sure what else I should use. I would preferable like something free, but I understand that most freeware has watermarks etc. Although, I don't want to spend some crazy amount like £500 (about £50 would be my budget.) Any ideas?