I defy anyone to say that one exhaust or the other is the best for everyone. That simply can't be true.
I'm an IT guy who works on huge infrastructure projects. Lots of money on the table. In order for a project to succeed you need to define success right up front. If you don't, then you can't tell me how to meet the objectives.
This definition of what's best for the 950 (or any bike) has a bunch of different ways to define "best".
1. Best Price - Cheapest Wins? Most Expensive Wins?
5. Best Looking (would need a whole big discussion as that is so subjective).
6. Best made (same as #5. Very subjective).
7. Most HP gained? - Need Empirical data. Must show dyno runs.
8. Most Torque gained?
9. Best "Bling" Potential (somewhat subjective... :-)
Or, as most would assume here, including me, some combination of all or most of the above. You'd have to do some sort of weighted value for each of the variables above.
But, for each individual owner.. you must decide your criteria. And I'm pretty sure your criteria won't match everyone else's.
I just got a used 2004 950 with < 7500 miles. It has a pair of Remus Aluminum cans with inserts that is way too loud for ME. I snagged a pair of nicely used Akros here for $600 to my door. I've had Akros before and like them a lot for their quality of construction, appearance, and mostly the sound. I like them with the inserts in. So, my "which one" is based on a few of the factors above but not all. Cost was a factor as well and I didn't want to spend $1100 for new ones. I've never seen a dyno run for the Akros. I just know I don't want to put the stock exhaust back on (I have it) because of the cats/heat issue.
Being the geeky engineer-type that I am.. it is impossible to define "best" that works for everyone.
Tom [Stating the Obvious as usual]