I've said it before, but I'll say it again:
Aadland caps feel more solid, but are a bit rough in texture (if that bothers you), and noisier. I also had a latch on an occular fail within hours of use; I'm sure Jon will take care of it, but it did leave me a little wary.
Tenebraex feel like Tupperware ... I personally really dislike their looks, feel, and well, almost everything about them. But they're quiet, and they work.
Word of warning though - the recommendations Tenebraex make for Bushnells can be hit and miss. I've had some on an XRSII which were perfect.
But just got some in for some LRTS/LRHS models, and the occular cap didn't fit properly with the diopter slightly extended, resulting in a broken Tenebraex cap - the screw simply split the plastic upon tightening.