TH170 is more useful in different cases, seeing as it can adjust to different heights, and 3 heights at that, which is useful to not have to change parts even. It is viable in defense, stamina, and balance combos, but 230, I find it to be more stable than TH170, seeing as 230 is just one or two pieces (one from what I've seen and looked at). 230 is better on more stable tips, like D, seeing as the wobbling can backfire at times. Like what Pcyborg said, I still find 230 to be more useful in defense combos, seeing as the attacks will be ineffectively hitting the spin track, while the defense type will just be up there, waiting for the attacker to lose its stamina. And added with Basalt, which is the most useful defense and stamina wheel to date, it is able to survive strong attacks, even from my VariAres. TH170 I find to be more useful in stamina customs. Being able to adjust to different heights is necessary I find for stamina types. 230 I feel can be too high, and can reduce the spin time of the bey drastically, so I don't feel that it's good for stamina types.
230 and TH170 are both useful in balance customizations also, depending on the circumstances and what height you need. Personally for balance types, I would use TH170, seeing as it can adjust heights, and change its "type" to whatever is necessary in the next battle.
Remember, this is what I've seen and how I've tested it, and the results.