Let's see. If I had to choose between a flaming pig, a Bibarel recolor, and another grass lizard, my first pick would be the grass lizard. I haven't really been fond of the fire starters since Cyndaquil. Here's the pattern I seem to have with starters.
Kanto: Fire (grass and water tied as my second choice)
Johto: Fire (grass would be my second choice, but I really don't want to see my beloved Cyndaquil in the hands of Giovanni Jr.)
Hoenn: Water (Grass was my second choice)
Sinnoh: Water (I don't care for monkeys, but fire would probably be my second choice)
Gen 5: Grass
Some day, I'd like to see a cat-like starter.