In general, carbon fiber is better than aluminium for the same weight tripod. CF tubing is stiffer than aluminum.

Of course if you compare a lightweight carbon fiber tripod with a super heavy duty aluminum tripod, the aluminum one may be steadier.

I have a gitzo 1325 CF tripod and a bogen 3051 aluminum tripod. The Bogen is sturdier, but it weighs over 12lbs compared to under 5lbs for the Gitzo, plus it doesn't pack as small. I think the Gitzo cost 2x or 3x as much as the Bogen, but if you have to carry it for a couple of miles, it's worth it!

I don't know what price range you are looking at or what lenses you intend to use, but for an excellent quality lightweight mid range CF tripod I'd look at the Manfrotto 190CXPRO3 . you can get the same tripod, but in aluminum and it's then called the Manfroto190XPROB 3. The aluminum version is around $150 and the carbon fiber version is around $300.

The lowest cost version would be the Manfrotto 190XDB 3 which you can find for sround $110. Just as sturdy but a few less bells and whistles.