That's Gen 4 for me, or Sinnoh rather.
I do recognize most Kanto/Johto/Unova songs though, but I can certainly say I'm able to whistle/hum along every single Sinnoh theme (other than ones I never encountered, like Arceus).
I blank on Hoenn/Kalos songs though, which is strange because Gen 3 is the first gen I played. (Although I played all the first three gens at the same times due to downloading all roms).
Sinnoh is just the comfiest for me, and reminds me of the best time of my life. ;_;