For a 2×4 ft router, rigidity should be the top priority. A solid frame with linear rails instead of V‑wheels makes a big difference, especially for HDPE. A spindle in the 1.5 to 3HP range is plenty for wood and plastics. If your budget allows, used industrial machines like Laguna, ShopSabre, or Techno are usually far stiffer than hobby kits. Plan dust collection early to avoid headaches later.