Lots of names mentioned I agree with but I'll mention some I haven't seen named too much.
O.Bonk & B. Akey are good ones, I think only mentioned once a piece. Svechkov I like +1 for Firkus and Mailloux too.
Haven't seen him myself but I know Pitt fans are high on Blomqvist (G)
Surin? Not sure he fits but I like him. Oliver Moore would be another in this category.
On the Hawks topic, I think Nazar gets a little underrated. I like a lot of their prospects - Kaiser, Kantserov (especially), Ryan Greene.
I think Van has something with Bains. I like Stastney too on NSH, and I feel like Molendyk flies under the radar. L'Heureux could be a real menace for them too if he keeps his head on straight, Marchand-lite.
I think LaCombe gets forgotten about in ANA. I think Jesse Pulkinnen will turn into a real one for the Isles too. Calle Odelius and Elias Salomonsson are also both quite intriguing.
Bischel should probably have more hype and Miromanov will probably be a mainstay in Calgary for awhile. I was down on Stromgren but he seems to have turned a corner too.
In STL I think Neighbours doesn't get the respect he deserves, and Matt Kessel should be a solid NHLer.
I liked Topias Leinonen in his draft year but haven't really followed him and you never know with G's.
Nicholas Moldenhauer which is surprising as a Leaf's pick. Daniil Guschin gets forgotten about in SJ too.
I'm an Avs fan and I've seen Ritchie's named mentioned a lot, so I'm not sure he's that underrated. At least he won't be soon. In our prospect pool I think Gulayev is going to be that guy, and Behrens and Kovalenko never get mentioned, but should both be middle of the lineup guys at least. I saw Ivan Ivan who could be a Lehkonen type if all goes well.
Anyways, just throwing more names in the hat. Should be a fun thread to look back on. If I were to choose the #1 underrated prospect amongst fanbases/the casual fan, I'd go Alexander Nikishin. He's going to be a monster but out of sight out of mind.