While gas giants do give you an advantage another way to look at it is what isn't out there. A no atmosphere start will give you an additional type of atmosphere to colonize that none of the races in the game "breathe" (unless you are using the neutral race expansion pack you can get from Universal Shipyards). If you go this way I would pick ice worlds because there are a lot of rock colonizing races out there. If you look at it from a research standpoint gas giant is again the way to go because gas giant colonizing races are very rare. You can of course change the atmosphere and starting colonization tech some of the races use to even it out a bit also.
Also if you play in an ancient galaxy there are not as many gas giants so you also have to know the part of the galaxy you are in
. I usually avoid ancient galaxies myself because I find the frequent black holes very annoying there. Its tough to find a clear path from point A to point B frequently. In a full tech start that wouldn't be a big hinderance though.
[This message has been edited by Tomgs (edited 30 December 2000).]