That's like asking which cigarette is better to smoke. Yea - it's a light cigarette, so there's a heavier filter on the cigarette - but it doesn't mean it's really any better or "safer" for you than a Newport.
The answer would be NO chemicals. I mean, if you're really interested in hair health than a relaxer shouldn't be in the question.
HOWEVER: that's to not to say you can't have some fabulous hair with some chemicals - lord knows there are some sisters on here with beautiful, healthy relaxed hair. It's a balance - the more chemicals you put on your head, the more moisture you're going to need to replenish. Relaxers break the protein bonds of your hair - so to maintain hair strength, protein treatments may become more necessary. Texlaxed, Texturized, Relaxed or Natural - understand your hair's moisture needs is going to make our break your success (because it is possible to OVER do the moisture thing). Moisture is your friend!!!