Scivation Xtend Perform seems to build up in the system (2-3 weeks to notice the best effects at 2 scoops), and I might add that Scivation Xtend flavoring is great to me.
I'll second the xtend flavoring. The black cherry xtend perform is great. Like ma70 said, takes some time for the peakO2 to have an effect. The ergogenix bcaa's have excellent flavoring as well.
Pretty much sums it up right there
In Perform we offer: Black Cherry, Mango and Fruit Punch (that would be my ranking in that order)
Regular xtend (Orange, Grape, Blue Raz, Mango, Fruit Punch, Green Apple, Pineapple, watermelon, strawberry kiwi, lemon lime, pink lemonade)
You really cannot go wrong with the Perform, if you have been following along we have had over a dozen logs on here and the changes in performance, endurance, and recovery on those individuals has been remarkable. There are quite a few on here that can vouch for it.
Some other great options:
Modern BCAA (USP Labs)
Core ABC (Core Nutritionals)
MAN Iso-Amino
Universal Juiced Amino's
People have noticed the changes in Peak02 in a matter of days.
Primaforce is going to carry it in bulk if you would like to just buy it separate and utilize yourself!
1Fast400 could shed some extra light on Peak02 and the research he has conducted