Bastet's LS is infinitely easier to get consistent x2.5~x3.5 multiplier; you need 4 combo to trigger x2.5, yet for Kushinada when you get 3 combo, you only trigger x1.5, so for the same power you need 5 combo. That's the biggest strength behind Bastet. Kushinada, for high-skill combo players obviously is the strongest of the three you mentioned due to consistent x49/64/81/100, but I mean, that's for high skill players. And Ookuninushi is just flat out not as popular as the other two as leaders.
The way I look at it, Ookuninushi has a much easier time getting consistent x4 than Bastet, while Kushinada will struggle to get x4 because a typical board will be possible to make 7 combo but either does not have the right number of orbs to match 8 combos or orbs are too far apart for it to be feasible.
Ookuninushi may get better with his inevitable ultimate evo, while a Time extend awaken would make consistent 6 combos much easier, the best case would be him getting a dark row enhance. 6 Combos with 1 row is pretty feasible with orb changers, but the true terror is the burst capability with Tsukiyomi CTW on boss stage. That, combined with the innate advantage of Dark over Green in general, may make him possibly the best of the three.
However, he is not waifu material material so his popularity... :V
Using a combination of Bastet and Kushinada has gotten me through lots of descents though, the balance between ease of getting to x14 and having an actual valuable active is great.
I remember trying double kushinada once, just x9 even at 6 combos made it really difficult to get to the boss stage.
Anyways, the point I'm trying to make is the three's LS have their own pros and cons but you can't really say one is better than another, but Kushi and Ookuni's actives are so useful they're often subs in other parties. Yet, bastet's active is pretty much unneeded outside her own party because rows are now a thing. (Even then, G/L Bastet with a focus on green row is totally do-able!)
Spreadcat's best use remains to be Wednesday Dungeon Legend.