Nothing that drastically changes the play balance.
i.e, no level cap increases if there is a cap, no vastly stronger monsters or equipment (Broken Steel/Zeta/Anchorage), etc.
Honestly, I'd prefer as little DLC as possible, but that's not likely given the modern gaming industry. (I'm still waiting for a "complete edition" of Mass Effect 2, to play the DLC. No interest in buying anyone's custom currency, to deal with their proprietary online store, etc, etc, etc I skipped most FO3 DLC, am not getting any FO:NV DLC, didn't get any Dragon Age DLC, etc....)