Because I've been playing the games since Pokémon Red on the Gameboy Color oh so many years ago Pidgeot was the first bird Pokémon I ever used (or would that have been Pidgey? Meh, whatever). As such it is little surprise that Pidgeot would be my favorite even today. I'm not entirely sure what drew me to Pidgeot to begin with, but nothing else has come close to replace my affection for it as my team's flier. If I could I'd totally have it on my team in every single game, but alas. I'll have to settle for an alt team instead.
The reason why I love Pidgeot is because of its simplicity––plus it is a bird Pokémon and it looks like a bird. Birds are awesome. Not a very convincing reason, I know, but one that works for me. Even though there are likely much better Flying Pokémon than Pidgeot it is always my first choice when it comes to having a Flying Pokémon on my team (which is pretty much a must for me). I've used many other Flying Pokémon in games where Pidgey wasn't available to catch, or have tried using other Flying-types in games where it was available, but I'm always finding myself missing Pidgeot. I just love it so much.
I also love Pidgeot's overall design. It looks awesome! The feathery plumage that goes down its head, and the black marks by the eyes, have always been my favorite parts of it and I think with the animations in Pokémon X/Y I fell in love with it again. When a Mega Evolution form for it in the then upcoming Pokémon Omega Ruby/Alpha Sapphire was announced...well to say I was "fangirling" may have been an understatement. I was downright spazzing (I still spaz every time I see it). *cough* What can I say? I love everything Pidgeot.