Gas Giants are the biggest, and since they can't have an atmosphere of 'None', are more likely to be your atmospheric type. Rock Planets are the most numerous, and have a greater chance to hold ruins than other planet types.
Is there **any** advantage to being an Ice-dwelling race?
I can think of only two advantages to being an Ice-ish race, and they only work in PBW:
1) Nobody picks Ice planets, so if you decide to get Ice planets, you have hardly any competition, if not no competition at all.
2) Nobody picks Ice planets, so everybody has to get in line & pay ridiculous prices, if they want to trade for your 'Ice Colonization' Tech.
Might Ice planets have better resource values, or better conditions, than other planets? There has to be *some* advantage to being an Ice-ish race