Speaker suggestions?

I recently purchased a vintage Sherwood S5000 vs1 with el84 output tubes. They dissipate about 20 watts per channel. I had recently purchased a pair of NHT Classic 3 monitors. They are a 3 way sealed box of medium efficiency. I really didn't think this would be a good match for this amp. I was wrong, they sound great. Go figure. My question is what other monitors should I take a look at with this amp?