18-55mm + 55-200mm or 18-105mm?

A year back I had the first two with my D3100;18-55mm VR and 55-200mm VR. Eventually, I found out that I was'nt using the 55-200mm VR much hence six months down the line I sold the zoom. I am enjoying the 18-55mm VR for now.

Recently, I get tempted on selling my 18-55mm and going for 18-105mm VR since many come up for sales on local craigslist. Time and again I read reviews indicating that the 18-55mm VR is sharper and better than the 18-105mm VR, hence I give up the move.

More better option I look for is a 17-50 or 17-55 from Sigma/Tamron so as to get a faster lens.
--
D3100, 18-55mm VR, Canon S95