I disagree with a fair bit of what you wrote here. But I want to preclude this by saying, I think both these players are terrific. Sandin’s power play usage is a feather in his cap, but Liljegren is more than capable of running a PP as well. He has done it very effectively throughout his career, just never had an opportunity yet at this level. His offensive instincts are also top notch, he just looks different doing it. He has an excellent first pass and shot. I’ll give Rasmus the edge in those two areas based on opportunity pp wise and some terrific puck work he’s made in the NHL so far. I firmly disagree however with the assertion that Sandin is better defensively, he definitely is not. I see a decent bit more maturity in Liljegrens defensive play than Sandins, but the latter has come a long way this year. Physicality, in terms of hitting people goes to Sandin, but I think Liljegren actually uses his body more effectively than Sandin does otherwise. Liljegren is also a better skater
It’s very close, but I think Liljegren has more of his overall game together and is currently the better player. They both excel looking a little differently, and that might be part of why they work so well together
As for what a team would trade for them, their value, I think the choice between if you were acquiring them is more of perceived ceiling than who is actually better now, and I could see why someone would potentially be more keen to choose Sandin in that scenario. But it also is likely a matter of stylistic fit
Either way, both ours and going nowhere soon