Garage sale NOW. Do NOT move things with you that you plan to sell/get rid of. Imagine the time/energy you will spend packing, loading, moving, unloading and resettling all the things that you don't even want anymore.
The only exception would be if you are moving to a higher traffic area (from rural to suburban) or if there will be a better chance of making money at the new home. AND if you have some specific large items to sell (dining set, weights/fitness machine, baby gear). If no, then its probably not worth the work for the $. Post big items on craigslist or the like.
We have made decent $ and poor $ with garage sales in the past and it really varied by location and having some big items to make a good sale.
ETA: The sale we had before making a move we made more than $600 selling a ton of items, and that was us selling things we had bought secoond hand. It was a great high traffic location and we had lots of big furnniture.
Our more recent sale we made closer to $150, even though we had some big items. We just weren't in a high traffic area and didn't get the same interest in what were arguably nicer/newer things.
Currently, we aren't bothering with the work. We'll just list big items and donate the rest.