Well let's see...
I like Rhyperior, and dislike Rhydon
I like Yanmega, and like Yanma
I love Gliscor, and like Gligar
I'm iffy on Magnezone, and I like Magneton
I despise Lickilicky, and I sort of like Lickitung
I don't know how I feel about Tangrowth or Tangela
I love Electivire, and I love Electabuzz
I'm iffy on Magmortar and Magmar
I love Glaceon and Leafeon
I like Porygon-Z, and I love Porygon2
I love Togekiss, and I dislike Togetic
I hate Ambipom, and I'm indifferent on Aipom
I love Honchkrow, and I like Murkrow
I love Mismagius, and I'm indifferent on Misdreavus
I love Weavile and Sneasel
I like Mamoswine, and I'm indifferent on Piloswine
I like Gallade and Kirlia
I hate Probopass, and I'm indifferent on Nosepass
I love Roseraid, and I'm indifferent on Roselia
I dislike Dusknoir, and I like Dusclops
I love Froslass, and I'm indifferent on Snorunt
I see no pattern. Can't see why people just lump the Gen IV evolutions all together the way they do.