I should probably start off by saying I'm not super familiar with all the roads on either of these routes. They do look like the most direct, though even a more indirect route would not be all that long.
VT 63 doesn't directly connect to US-302; if you want to head that way, it would be better I think to go another exit and take VT 62 (which is a nice wide two-lane highway). Otherwise, that looks to me like it ought to be a decent route. You could also take US-302 to I-93S.
If my vague memory serves, NH 118 I think may have been a rather hilly and curvy road. I could be confusing it with some other more minor roads in the area. US4 to NH 104 to I-93 would be a decent route to take and I think maybe preferable to 118 and 25.