I travel on business to Enns regularly for a couple of years and I know all the hotels here.
Gasthof Brunner (also known as "Zum Goldenen Schiff") is one of the best choices here. Location excellent directly at the Hauptplatz. Parking overnight right in front, but through the day only short term parking is allowed here so you need to move your car to another parking (nearby). Bed/mattress quality, cleanliness, bathroom, noise - all with no complaints. Very pleasant small simple restaurant (although not the very best in Enns), nice to sit here in summer outside (tables on the street), drink white wine and observe the life on the main square of this ancient town of Upper Austria. Breakfast simple (cheese, ham, butter, jam, orange juice). Use to pay EUR 40 for single room/single occupancy. The best value/price in Enns. Recommendable.