I founnd that the Tetra one worked well for me,i did get the Nutrafin free with my aquarium (that was rubbish),but the Tetra one........is it safestart?,that certainly helped speed up the process.Don't knock it unless you have tryed it!
i used to use the bio-spira by marineland before Tetra bought them.. i believe it worked. we added the bio-spira, waited 24 hours tested the water and added fish, no problem. i don't trust Tetra's version as well because they no longer keep the stuff refrigerated which to me means that the bacteria is able to be exposed to heat, which i know kills it.
i know lots of guys that swear by seachem stability, but i know nothing about it and i've never used it. it has been recommended to me by many fishkeepers that i trust though, so it can't be all bad..