Silicone is the best material IMHO, mouspads are neoprene usually but it can become brittle over time and disintegrate. I bought a Silicone wineglass dryer at Target cheap and cut it into multiple pieces and it makes an excellent waterproof vibration damper, especially because it is ribbed. I went with a Laguna MaxFlo 1500 pond pump which has no base so this worked really well as a base/vibration damper:
A simple silicone trivet would work too. Filter pads work well but they collect detritus even if not in high flow and might need to be cleaned occasionally.