I don't think it matters
Suppose I sold lamps and imagined that people would easily find my site if it's name were www.lamps.com
But someone already has that.
I say that I am doomed. No matter what other extension I use, the general public (nearly half of which do not believe in evolution) will enter www.lamps.com
Like it or not, dot-com is the only extension.
The exception is sites people need to get to via detailed written instructions, such as dot-gov, and sites which depend on being found by Google/Yahoo which could be
www.g342.abkre43.tk or whatever.
Bottom line: If you expect people to remember your URL, it better end with dot-com.
Better that Lamps.net would be NiceLamps.com or BestLamps.com