By whatever your buying process actually varies on. Vertical carves win where the sales motion genuinely differs by industry; geographic carves win where meetings and time zones matter; product carves win where expertise is the constraint. Most companies end up with a hybrid, which is fine if the cut order is explicit.
Whatever you choose, normalise the account values before balancing, and never cut below the metro — splitting a city between reps generates disputes that outlast the plan. Publish every rule before the map is announced, including how holdouts and named accounts are handled.
Every claim above comes from work LeanScale published. These are the sources.