1st Gen for me: Charmander>Bulbasaur>Squirtle (although Blastoise was more useful in the end than Venusaur)
2nd Gen: Totodile>Cyndaquil>Chikorita - I liked all 3 actually! Again though Meganuim was next to useless when it mattered
3rd: Mudkip>Fire un lol, soz yed's gone!>Treeko - x4 weakness to grass (but who uses them?) but otherwise Swampert is a beast! Ditto Blaziken - fast as fook!
4th: Turtwig>Chimchar>Piplup - Don't rate Empoleon, Infernape's right up there with a Blaziken, Torterra prolly the best starter of them all imo!
5th: Only tried Oshawatt, my two kids have the other 2, not gonna pass judgement here....