Biased towards shrooms xD
Plus it actually helps in the 5th gym too. Not to mention, it's easy to find, and relatively quick to evolve.
Geodude is fine, but kind of useless w/ crappy stats and typing. Get it to a Graveller, and then that's it. If it was Golem, then THAT'S something I'm okay with. To it's credit though, it's decent in helping out w/ gyms 4 and 6.