Voyager when in the US and most of Canada. Great product, and there is a freeware version that does not have some of the features of a subscription, as terminal charts, US Low/VFR charts, etc., but what may be the best of all, I can also export a flight plan to FSX with the paid subscription! I sprung on a limited time subscription a while back, which provided me all the terminal charts and Low/VFR charts. 'One time' paid subscription was just fine, as I do not need the most current updates...this is FS.
When outside the US, I've been using Plan-G, and find it to pretty darn good, but then have to go hunting for the terminal procedures I need on file.
Both utilized on a second PC or laptop via network.