Well, it depends on what deck you're playing, and why you need to counter it.
For example, most people use Blaziken FB to counter Dialga LV.X in DialgaChomp if they need PokéBodies for their deck to function. However, if you need to counter it for a different reason (for example, just because it's a good SP deck that's a bad matchup), then Blaziken won't be as good.
Also, some techs can be worked into some decks better than others. Against Gyarados, LuxChomp typically techs in Lucario GL (to make Gyarados' weakness x2) and then a Crobat G, to OHKO Gyara with Flash Bite+Flash Impact. However, Lucario GL won't work in most other decks...