If you have the resources at hand, attending both Gettysburg events might give you a great side-by-side comparison, since each has a slightly different focus. They're only a week apart and might be very educational. As previously and oft-mentioned, 'best' is a subjective term. I would suggest, (again, resources allowing), to try and take in a couple of smaller living history events. Assuming you live east of the Big Muddy you can probably find any number of decent little weekends in your area. If you're out west, they still exist but just might take a bit more searching. You might even contact a unit, and with some rudimentary training and loaner gear, fall in with us. Nothing will give you the taste of reenacting like that pinch of black powder from tearing a cartridge with your teeth.
Good luck, and after you complete your research, I'm sure several of us would be interested in reading your thoughts.
-GG grandson of Cpl Christian Greener, 1st Wisconsin Cavalry, Co. F
-Rob Weaver is my guru:
-"...one of the characteristics of a good reenactor is the willingness to not be bulletproof."
-"Be more concerned with your own impression than with anyone else's."
-"Be a joyful and competent warrior and other reenactors will want to be around you."