I, for one, have never liked the first three starters in the games actually. In the anime they're all cute and cuddly and have awesome personalities, but in the games they're just not good enough. They decimate in R/B/Y, of course, but in every game that has come after them they're mediocre or outright bad. Venusaur's the only one that ever sees the daylight in competitive playing and even then it's outclassed by too many of its brethren. It's a shame, but that's how it is. Poor Charizard is practically obsolete. Not that I'd be whining, though. I love Stealth Rock to death.
And since we're doing listings, I'll just leave my own here, hoping I'm not the only one here who likes to read the lists of other people as well.
Fire: Blaziken - Fire pokémon are generally meh-esque. They're cool, but weaknesses are terrible and they're most of them are super frail. Blaziken strikes so hard that it can't be ignored, however. And it looks cool. I love it.
Water: Vaporeon/Gyarados - I used to hate most water types, with few exceptions like Gyarados, Quagsire and Gastrodon. Then came Gen 5 and I ended up using Vaporeon in competitive. It tanks like a beast and heals my other companions like no other.
Grass: Meganium - I've always loved every single Grass pokémon there is. Breloom, Victreebel, Ferrothorn and many others have been a part of my team, but Meganium beats them all. It's cute, it's sturdy and even though it's kinda bad in competitive, I many good memories involving playing with Meganium. Nostalgia trip~
Poison: Nidoking - Poison's a kinda gimmicky type. There are some pretty cool things out there, but most of the time they're quite worthless. Nidoking was a must have in RBY, so I'll just drop his name here.
Rock: Tyranitar - 'Nuff said, I think.
Dragon: Salamence - My favourite pokémon of all time. Powerful, outstanding and cool.
Ground: Sandshrew and Sandile - They're both adorable. I've always liked Ground type, but I rarely have any ground critters in my team. Rhyperior and Krookodil are the only ones I've used so far.
Psychic: Sigilyph - I've never liked Psy that much. It's too weak and gimmicky to fit my straightforward style. Sigilyph looks amazing, though. He might just be my favourite Gen 5 pokémon.
Bug: Heracross - Listing the likeable pesky fighter here so that I can leave space for Lucario and Scizor.
Fighting: Lucario - Nifty, and can take some hits. Pretty fun to use. Mienshao is really cool too.
Dark: Weavile - I already listed Tyranitar, so Weavile gets to be my favourite Dark type.
Steel: Scizor - Steel's another type I've always liked. The defensive aspect is nice, but the different-from-everything-else offense some steel types, like Metagross and Scizor, provide is pretty cool.
Ghost: Haunter - Solely for anime reasons.
Normal: Furret - I had a level 100 Furret back in my first silver game. I get nostalgic every time I see one of them.
Ice: Spheal - Endearing.
Flying: Anything but Fearow goes.
Electric: Ampharos - The other part of my dynamic lvl 100 duo back in silver. Nobody took a Zap Cannon and was left standing. I love Electric types anyway. It's a shame they're quite weak.