I dont think its a stretch at all to think Pulujarvi is the second best prospect picked by Edmonton. For me its between him and Hall. Hall was #1 pick and dominated in OHL, plus super good WJC. But even at draft hockey sense was a bit of a concern ( that would limit him from being elite star, but wouldnt hold him back from being a top NHL player)
Puljujarvi is harder to gauge because he was playing in a pro league and on one of the better teams. His TOI and quality of comp is vastly different than Halls. So tough to compare straight up numbers. In WJCs (small, small sample size) Puljujarvi did do slightly better fwiw.
Going from tools:
Size: Puljuarvi
Speed: Hall
Skating: Pretty even when taking into account overall agility
Smarts: Puljuarvi rountinely gets praised for high, high hockey sense. Hall had killer instinct, Pulj has questions about whether he will be a high level finisher in NHL
Shot: Pretty even. Hall had an elite shot coming in, but was regarded as more of a power shot versus an accurate one. Puljujarvi has same critiques (that he is growing into body and shot is more powerful than accurate)
Hands: Pulj
If you go by tools, you could make argument his tools are above Halls at same age and could make him better if he can put them all together.
As for RNH and Yak (and even LD), he is a combo of all 3 almost. Yak and RNH were both weaker #1s and had noticeable holes in game (size for RNH, smarts for Yak). Puljujarvi is like a combo of both those guys best features, but 6'4.
LD had similar great tools, but his skating was a big ?. Pulujarvi is like a bigger, better skating LD who likes to shoot more