Your idea of a biggest win is different than mine. I consider the best fighter a person has beaten as their best win. Franklin, Rumble, a KO of a prime Wanderlei Silva in under 1 minute. Destroying someone like Tank back in the day who was huge compared to Vitor. Gilbert Yvel, Akiyama.
These are all better wins than what you are giving.
Hitorgethit, this is not directed at you per say but, generally people say Bispings wins are unimpressive, to be honest comparing the caliber in these lists i don't think the quality is too far apart, i would probably agree Vitor edges it, but people shit on Bispings record to often.
Stann is a solid win by most peoples estimations. Leben's solid but his respect was stolen by Bisping - before that fight he was classed as a respected power puncher now he's considered a joke. Denis Kang came over to the UFC with alot of hype - as did Jason Miller, and the Rivera/Akiyama are decent wins.