[Jotaku]

If we assume that attack point, critical rate, everything are same only except attack speed and life steal stat of some 2 builds, and if those 2 fights each other as a duel, then a build with life steal usually wins a build with attack speed in Eternal Return.

However, there are more advantages of using melee speed over life steal. That is, it just damages faster, very effective against non-melee types such as types of bow, magician, etc. Since not all players use melee characters, there are still more advantage of using melee attack speed over life steal. Moreover, attack speed is more efficient in battles where the situation is urgent.

Here is the video demonstration why life stealing is strong in melee fight. If you check how Fiora fights like against an enemy team with 2 melee characters, Yuki and Jackie, you see that Fiora frequently try to recover HP by attacking with life stealing but those Yuki and Jackie don't have life stealing in their melee builds:

Notice that Yuki and Jackie had higher level and weapon levels about 2~3. This is why life stealing is strong in melee fights, but melee fight only.

Again, remind that melee attack speed still works very usefully in a variety of situations, far more than life stealing.
I mean you might want to mix them if possible, but more focus on attack speed.

[Jotaku]

Post updated as of May 22th, 2022.