depends on
* what You use now
* what brightness You need
* runtime
* size/weight
* if it were a bonus to have a good handheld flashlight also (dedicated bike lights tend to have larger battpacks, usually in an external pocket)
for me, the single XR-E light is enough for trail riding (an ordinary headlamp added for very rought terrain).
Makes 2+ hours at full + an additional 18650 as spare.
Bombproof, extremely small but light, multilevel, ...
You might have heared already: Jetbeam, Fenix, ...
if this is not enough light for You, You will have to get a quad-led light (Seoul P7, or Cree MC-E powered).
In that case, handheld is not the best option because of runtime and/or size. The light should at least use 2*18650 batteries, better were one with an external pack.
PS: DX and similar are good to get a 1st impression, good to lend them around and save Your good lights ...
... but parts, electronics, machining, finish and quality control are related to price. Do not consider them as "good led light" and - for sure - do not consider them as rugged and no-problem-parts. Have Your soldering iron ready and learn where to get good drivers and led