Re: atmosphere / type of world handicap
 

I'd say the best choice from a "competetive edge" perspective, would be to figure out the least popular combo, so you have the least competition. Of course, the random variation is going to drown out any minor difference that might exist, and if any did have an agreed edge, more players would choose it and end up struggling over it. Not that it often makes all that much difference in the unmodded game, anyway, unless you choose the options restricting colonization, because colony tech and colonists are so easy to steal or trade.

PvK

Re: atmosphere / type of world handicap
 

it would seem gas giants would be a safe way to go. i havent encountered very many races that use that, most seem to be rock.