I am driving Thursday, 3/2, to Reston. Which is the best route after Gettysburg, Rt 15 thru Leesburg or Rt 15 to 270? I have never driven either route before. Please advise as to pros & cons of each. Any advice will be appreciated. Thankyou.

I am driving Thursday, 3/2, to Reston. Which is the best route after Gettysburg, Rt 15 thru Leesburg or Rt 15 to 270? I have never driven either route before. Please advise as to pros & cons of each. Any advice will be appreciated. Thankyou.
There are a few ways to go...just a matter of preference I think.
We take 81 actually all the way from Scranton. We feel the super highway is faster and still provides gorgeous mt. views. For Reston, we'd cut over on 66 in Va. The traffic on 66 is only bad when people are commuting East in the a.m so just don't go East till after 9 or 10 a.m.
But prepare in case there's dense fog anywhere between Hazelton and Harrisburg. We have often made a stop in Hazelton for Friendly's or Damon's if we stay overnight...and, lately, for the late movie in the newer looking multiplex with stadium seating, which makes a nice change of pace.
I81 to South of Harrisburg
Take 11 East to 15S
Take 15 S to Leesburg
Take the Dulles Greenway (toll) to Reston.
We've come back from Upstate NY that way a few times without issue. I81 to I66 is nice road but out of the way. You can make good time in Rte 15.