If you are ubering to/from the Magic Kingdom, the Contemporary is much better.
You can also monorail to Contemporary after and order Uber if you can't walk far after a day of parks.
Grand Floridian is ideal Uber drop off if you don't want to walk before day of parks. But, it's not a long walk from the Contemporary.
If you're staying at a Disney resort, the busses will get you closer to the Magic Kingdom. If your resort only has a shuttle to the TTC (such as one off site), Uber to Contempo will be much faster.