so i'm thinking either 4 nights in january or i can stay 6 nights in feb. the week of presidents weekend. is it better to go for longer but bigger crowds or fewer days at a less busy time?
When we are only talking 4 nights vs 6, I'd choose the less crowded dates as 4 nights is plenty of time to see everything, and I always find the parks more enjoyable when they aren't wall to wall people.
It's not even the wait times that get to me. It's just missing out on the little details because you can't see through all the people. Also, the constant surrounded on all sides can't easily move feeling, I hate that. I want to be able to wander around, take in the details and Easter eggs on buildings, enjoy the street performers, and take lots of fun pictures.
The other factor for me personally is that when we do longer Universal only trips, we spend quite a bit of time pool hopping or at the water park. I know for us Jan / Feb is usually too cool for that, so we don't need as much Universal time as a summer trip.
Having said that, I'd check the crowd levels forecasted for the other days you plan to go around President's weekend. If they are low to moderate, it might still be worth doing. If you have 6 days and only half of them or less are busy, you might not mind the couple of crowded days.
In addition, the parks have much longer hours on the holidays, so you'll have more time in the parks to offset the higher crowds. This opens up opportunities for night time rides, dinner in the park, and longer lunch breaks which might be positives for your group depending on your touring style and interests. February is also Mardi Gras. There will be concerts, food trucks, and the parade is amazing, so there's all that to consider as well.
Lastly, if you haven't already do some price comparisons. I can tell you right now that would probably be my number one reason for going in January instead of over President's Weekend. I'm not sure I could afford it, especially if I wanted to stay in a premier restort to get the EP which will be needed for those dates.