Where MDF works well
MDF is consistent and machines into crisp paint-grade profiles. Long lengths can reduce joints. It is best kept away from persistent moisture and must be handled carefully at vulnerable edges.
Where wood earns its place
Solid or finger-jointed wood offers better fastener holding at some details and can tolerate minor moisture exposure better when properly finished. Stain-grade work requires thoughtful grain and colour selection.
Movement and finishing
Solid wood expands and contracts across its grain; MDF also responds to moisture, particularly at cut edges. Acclimation, suitable primers and stable indoor conditions matter for both.
Choose detail by detail
There is no universal winner. Baseboards near wet entries, curved work, deep window stools, painted crown and clear-finished casing may reasonably use different materials in one project.
Save the selected samples, marked-up drawings, quote and written changes together. A shared record is one of the simplest ways to avoid misunderstandings.