Watched Landry with great interest when BC played Notre Dame and he was completely dominated down after down, total nonfactor. Reminded me of former Packer draft pick Jonathan Brown.
Landry has been banged up this year. Look at him the previous year, to get a better idea of what he is capable of. The drop in production this year is also why some sites have him falling out of the first round. Like every early pass rush candidate for this years draft, he has things you don't like so much.
With Landry, it is this years level of production, with Davenport it is running the edge round the tackle, with Key it is bullrush, converting speed to power against OTs, with Edmunds it is playing OLB rather than inside (he is not a full-time OLB), with Okoronkwo, he is not that talented in pass coverage. These are generalisations, but have some truth to them.
You have to go with whichever prospect, whose limitations you feel you can live with.