Take a look at my signature... have any idea which pokemon I prefer?
To be honest, both Pokemon aren't really nostalgic for me. Whimsicott can never be nostalgic since it's Gen 5, but I used it in game a lot and fell in love with it. I had a few Jumpluff cards, but I never used it in game. The annoyingness is the main theme of these two mons. If you've seen any of Shofu's videos, you'll know how annoying as heck Jumpluff is to handle. The same goes with Whimsicott, but I like Whimsicott better in battle. (It sweeped a team of 6 legendaries with Stun Spore/Leech Seed/Substitute/Hurricane. Admittedly, it was against an inferior opponent by a long shot). Honestly, though, the design is the main difference. Jumpluff honestly looks like an Oddish (my favourite Gen 1 grass type) with a few odd-lookin' balls around it. It's just such a horrible-looking Pokemon.
Whimsicott, on the other hand, has a nice balance of cute and cool. It's a frickin' spore ram! I mean, don't you just want to snuggle right up next to it... admittedly, the Gen 5 sprite doesn't do it justice, but that doesn't take anything away from the design.
Whimsicott