Comfiest Flying Pokémon would probably be Altaria, seeing as you would be sitting on a cloud, basically.
Lapras still remains the best Surfing Pokémon for both comfort and speed.
For land travel, while Rapidash would certainly be one of the fastest, Mudsdale would be the best option across rougher terrain.
For going across snow and ice, then a Pokémon like Beartic or Avalugg would probably be best.
Imho, of course.
