NEMA 17 is almost always the right answer. A hot wire pushing through foam needs a tiny fraction of the torque a printer or router demands, so the common 17HS series (around 0.4–0.5 Nm) is overkill already. NEMA 23 adds weight, cost, current and heat for torque you will never use, and forces bigger drivers and supplies.
Pick a 1.5–2 A bipolar NEMA 17 and run it at low current (the motors barely work), which keeps everything cool and quiet. Spend the money you saved on good belts, square towers and a proper wire tensioner — those affect cut quality; motor size does not.
Pick a 1.5–2 A bipolar NEMA 17 and run it at low current (the motors barely work), which keeps everything cool and quiet. Spend the money you saved on good belts, square towers and a proper wire tensioner — those affect cut quality; motor size does not.