Both would be nice, but my favorite was Cabana Conde to Adagua if you have time for that one. Three days really isn't enough time though.

Here's our album for Cabaconde-Llauar-Sangalle so you can see photos of parts of both your suggestions:

http://www.summitpost.org/album/365290/ ... galle.html

Here's our album for Cabana Conde to Andagua if interested:

http://www.summitpost.org/album/368650/ ... -Trek.html

If interested, here's the trip report for both:

http://www.summitpost.org/trip-report/3 ... -peru.html

Anyway, it's not hard to do Sangalle/Oasis and Llauar on the same trek.

There isn't that much fauna other than the spectacular condors and a few lizards unless you do the trek over the mountains to Andagua (in that case there are many llamas, guanacos and alpacas.

How is Llahuar compared to Oasis?

Llahuar is less developed, has a neat geyser not far away and wonderful hot springs. Oasis is more developed, perhaps slightly prettier and very nice waterfalls and cool/cold pools to swim in.

Llauar:



Sangalle/Oasis:



I would suggest seeing both on the same trip if you have the time. Are you tied to 3 days?