Hollywood Studios is a half day park and Animal Kingdom is a quarter day park.
Universal arguably has at least one half day park (both could be argued as one), but more like 1 and 1/2 of a park in total.
At Disney, I’m fine with someone saying AK is a 1/2 day park, HS a 3/4 day park, and MK and Epcot both a full day park. Though, it REALLY depends on what you’re doing.
IF you love the shows and do all the AK shows in a day, as well as doing planet watch and the walking trails, AK is definitely a full day park. Now, if you only like rides, it would be a half day park.
US is fairly comparable to HS. Though I’d argue that many of the US rides lack re-rideability, that is simply an opinion, nothing more. Now, by said comparison, Universal is at 3/4 of a park. Going to Islands of Adventure, there is more to do… for some. If you can do all the rides there, there is a decent selection. However, it’s hard to consider it a full day park compared to MK (unless if this scale can go past a full day).
NOW (and this will be the last point), if the value of a park is derived from how long it takes to do the rides, you can do all of the rides at either Universal park in roughly five hours without express (mileage may vary, though it’s pretty consistent for me). If this is the way of measuring, Universal Orlando only has truly one full park! It’s hard to compare, but I don’t think we should rank a park by the value without at least comparing it to the suggested alternative… if Walt Disney World is a three-park resort, what would you put Universal at? How do you find a way to measure value (as it can vary significantly)?