Personally I’d say flying is the greater faff, and greater risk too if your bike ends up delayed or wrong destination and ruins your trip.
Other than that, box is most secure but a lot more faff to pack and check carefully it fits. You might have to pull everything apart with a box, including forks off (friend had to take rear shock off also as support pillar went right through where the shock was!).
Box weighs a lot more so you’ll be guaranteed over a basic 23kg limit if it’s a mountain bike + box, before you’ve even put anything else in it. There’s a blog somewhere from a rider who has also worked in baggage handling and said big problem with boxes is they slide off the conveyer ramps, dropping to the ground. Sure enough, friends spotted boxes doing just that on the last trip.
Bags are lighter but potentially more of a risk of damage. That said a good Evoc is pretty reliable. Less to pull apart potentially. My Evoc was fairly easy. Still though it’s an extra faff to be doing bike assembly the day you arrive instead of heading to the bar.
Drive, and you can take what you like, no weight limits, very little restrictions on CO2, liquids, sprays, etc. Loads of tools, spares. You just need reliable transport that’s in good condition and a recovery policy that will sort you out 😉
Plus it takes longer. Though depending where you live from the airport and comparatively the channel (if heading to Europe), it may not be many more hours compared to door to door flying when considering transfers/parking/taxi, the two hour wait before flight, extra hour other end to get out of the airport, etc.