Gen V: Emboar is by far the most horrible Fire/Fighter and Samurott is the very definition of bland. I like Serperior and its a fun dual screener but its movepool outside of that is horrid.
Gen II: Just kinda averageness all around. Meganium is definitely the worst starter of all. Feraligatr was bad until the physical/special split but now its ok and can learn Dragon Dance which is fun. Typhlosion is nothing special compared to other fire Pokemon and starters.
Gen I: Iconic but otherwise just ok. Charizard is pretty good in game, Venusaur is still pretty unique despite a common type, Blastoise is pretty ordinary, it would be interesting to see if it gets Shell Smash one day.
Gen III: Swampert is one of the best starters if not the best. Sceptile is reasonably unusual for a grass Pokemon and has a good movepool. Blaziken was great until Infernape came along, forgetting DW abilities.
Gen IV: Easily the best for me. All three starters are useful and interesting. Empoleon is just about the coolest thing ever and Torterra's got an awesome type combo. Sure Infernape is too similar to Blaziken but at least its better.