As I mentioned earlier:
Indirect fires (mostly artillery) are the main killer (80-95% of ground combat KIA), tanks are the main enabler for rapid manoeuvres in harms way and infantry is and will be the force of choice when difficult terrain and short lines of sight favour it.
Now one might ask whether I would seek decision by attrition or decision by manoeuvre.
I suppose the answer depends a lot on the geography. The more geographically constricted the friendly and the more cohesive the opposing forces are, the more attrition will tend to decide the outcome.
Attrition may on the other hand be understood as an enabler for manoeuvre (battlefield shaping). A manoeuvre battlegroup may be able to get into an advantageous position and succeed with a surprising manoeuvre based on the attrition success that the opposing manoeuvre force became less mobile after having its bridgelayers blow up, for example. More likely, heavy casualties during scouting and advance guard movements may make the hostile manoeuvre battlegroups timid, predictable and less secured - thus enabling their defeat by less inhibited battlegroups.
Attrition may also make manoeuvre in harms way possible in the first place, such as by defeating a timely detected ambush position with an artillery mission.
"Attrition vs. manoeuvre" is one of the old if not ancient debates, much older than the "wheels vs. tracks" debate and much older than its 1980's '2nd generation warfare and 3rd generation warfare' incarnation.
Manoeuvre has one extremely tempting promise, though: It would - if done really, really right - end a defensive war without loss of sovereignty within the shortest possible time or with the smallest possible losses.
The British Empire/Commonwealth defeated the Italians in Libya not by First World War-style artillery battles, but by manoeuvre. The Italian prisoners of war alone outnumbered the Allies' dead and wounded more than 70:1. The Italian dead and wounded did so "only" by less than 10:1. No cannonade between European forces has ever achieved anything similar, while several other campaigns that were coined by manoeuvre did.
The same ground forces that inevitably are needed for decisive manoeuvre (the tanks) are the embodiment of military aggression in Europe. At the same time they're necessary ingredients of the only course of action that allows for a quick and not very bloody end to a hot conflict in Europe (without sacrificing sovereignty for peace).
*: On the other hand, such lopsided results are typically achieved if one party is vastly superior in quality (the Italians had much inferior heavy weapons and AFVs and only partial motorisation). A one-sided cannonade would yield lopsided casualties statistics as well.