My only 10k egg so far (and I've been playing since launch...) gave me an Eevee. I already had all three Eeveelutions at the time and I don't care about IVs/stats/battling or Gyms in general. My egg luck has been out-of-this-world bad.
I did get a Tangela from a 5k egg and I've only ever seen one wild one (and it was way after I hatched that egg), so that was nice. I think the only other decent egg hatches I've gotten are Omanyte and Bellsprout, but only because I still need candies for their respective evolutions. :/
My Pokédex is sitting at 108 (110 once I do my next mass evolution spree) and I'm definitely hitting a wall in terms of progress. There's just very, very little diversity around where I live (Koreatown, Los Angeles) - all we have are endless Sandshrew, Growlithe, Machop, Rhyhorn, Geodude, Ponyta, and Pinsir, with the occasional evolution(s) of those Pokémon and the odd Rattata, Pidgey, Exeggcute, Charmander, or Spearow. The only reason my Dex is as filled out as it is is because the game came out right before my busiest travel month of the year, so I got to catch Pokémon in a lot of places I don't normally go.
That said, I did get a surprise Aerodactyl from a random lure while I was out walking last week, so that was a sweet surprise.