I just read through the manuals for both and from what I could tell the Favor (I was looking at the manual for the Favor S) seems to be the better of the two but not by much.
The companion seemed like it had a graphic display for decompression stops if one finds themselves in a position where they incur a deco obligation. But it does not seem like there is an ascent rate indicator which to me is more important.
The Favor indicates deco but not with little bars on the left side....and it does have a graphic ascent rate indicator.
I think other than that the two are extremely close in functions. Unlike the generation of computers that came after these that have both a personal conservancy and altitude adjustment, these two computers have altitude and you adjust the altitude setting when diving at altitude or you want to make the computer more conservative to suit your self (no separate personal setting).
Which ever you purchase, make sure you personally check that the computer functions because once the battery is completely drained or removed for more than 30 to 60 seconds the computer bricks and cannot be restored. Suunto does not offer any support for these.
The battery is CR1/2AA and the o-ring for the battery cover is size 023 and 70A durometer.
I was given a Suunto Octopus II computer a handful of years ago that had a dead battery. I purchased a new battery and o-rings only to find out the darn thing was bricked. I vaguely recall reading that the computer's program is stored in the volatile memory module so once without power for a period of time the programming is lost.
I don't think either the Favor or Companion is a bad choice, but I would not consider them all that good a choice either, but I suppose they would suffice as a backup. I still recommend purchasing something more up to date.
Just my thoughts.
-Z
