Work on learning how to do all of them. You should try to develop the flexibility to be able to rush, turtle and boom depending upon the map or the matchup.
Overall I think raiding is best. It allows a nice semi boom (like turtling) and is a great economy of force. Because you are the aggressor (unlike with a turtle) you get more map control and better access to fast food and other resources with only a small expenditure of resources.
I dislike turtling, I really feel that unless you have a specific reason for it (fast fortress for cannons, dragoons or something) that it is a waste of resources. Whenever you spend resources on military units and then dont use them, it is a waste because you could have spent those resources on villagers or eco upgrades that will pay off huge later.
Rushing is fun but it is an early gamble. Although it gets alot of publicity and works great vs a computer, remember that with a rush you always have to hurt your opponents economy more than you hurt your own by building a large force early. In RTS games with shooting buildings and such, the human defender will always have the easier time than his rushing opponent, so rushing requires more skill from the rusher.
Booming is great if you survive. The early boom (even with only 1 tc) allows you to get so far ahead of a non-booming opponent. But against person of reasonable skill a naked boom will be detected early and then you'll get killed.
Try to figure out what your civ can do well and also take into account your personality. The biggest thing is to have fun.
Edit- check out TGE's link, it's to a nice article on RTS game playstyles.
[This message has been edited by WolfLord_Arctic (edited 09-13-2005 @ 04:51 PM).]