As most are calling out, Lambert stands out as the most pro ready - lot of skill and the added weight (although not a ton) seems to give him a little more stability. Doesn't seem to be very concerned about taking a hit - maybe a bit too casual out there but I'm sure he'd be more aware if playing in the bigs.
I'd bring him up as a 4th line center and slot him into the second line with Cole and Ehlers here and there - let him get a taste of 4th line work and 2nd line skill. There's really no reason they couldn't take that approach.
Yager is the other guy that stands out but in a different way - he's looks like he's not out to impress anyone in a big way. He's very mindful of who is on the ice and the opportunities - but he doesn't force anything. Really like that approach for a guy his age - looking very promising.