I think it's kinda close. I think they are quite similar. Neither one was/is flashy, but quietly goes about getting her work done.
Offensively they can both work in the paint and around the basket, they could both shoot out to the 3 point line, both could drive to the hoop. I think Tuck was a better 1v1 defender, but Collier is a better shot blocker and rebounder. I think Tuck had a higher BB IQ, but Collier is much more athletic. (not sure how it would have been if Tuck didn't have all the knee problems). Tuck was a better leader.
I'd wait til after Collier has 4 years, but I think she'll win out, based mostly on her athleticism. Gonna make her offensively and defensively more potent. Although I think we sometimes underestimate how good Tuck was/could have been. Besides her knee, she was also overshadowed by playing with the 1 of the 3 GOATs and #1 -4, and arguably the #1-1 (Jefferson or Bird). Collier is getting 2-3 years to be one of "the stars". Tuck was like the Rodman to Jordan/Pippen, while Collier gets to be the Pippen. So it's easier to stand out.
(as an aside, I'm really, really looking forward to KLS/Collier as seniors. Cause right now, while they are really "the stars", they are still differing to the seniors and really good ones in Nurse/Williams. However next year as "the stars" and seniors.....the world will be their oyster.)