W.Len has a few issues.
A. She has no air range. j.A is her only decently ranged air normal. j.B and j.C and j.2C have jokes for range.
B. Her ground pokes kind of suck. 5B and 2B are good, 2C has horrible range, 5C doesn't have the nice range of Len's, and such.
C. 2C 623A whiffs on Len, W.Len, and Warc. She is horribly gimped from this.
Ren, on the other hand is arguably top tier. j.C is godlike, j.A is godlike, j.B is great, j.2C = free fuzzy guard. Black cat is DANGEROUS. Her EX Ice combos hit hard too, and EX Ice is a every way tech punish (okay W.Len has this too but she doesn't have as much techable stuff.)
At least W.Len has 214A. I like how I say Ren for Ren but W.Len for W.Len.
Oh, also, if for whatever reason you have MBR around, check out this combo for W.Len.
214D (yes, her shield bunker) [5A (one hit) 236B] x2 5A 236C dashin [5A (one hit) 236B)] x2 5A 5B j.BC dj.BC airthrow.
I love it. Works at least on Nero. Well, the 5A 5B j.BC dj.BC flat out might miss randomly. Have fun with that.
Other variations are something like this.
2B 5A (two hits) tk j.236B (this is extremely hard and must be done on the first airborne frame) 2B 5A 236C j.BC dj.BC Airthrow.
This one just shows off how awesome j.236B into 2B is. It's also very, very hard. And you have to do your aircombo off of 236C because you use your jump cancel.
A few other interesting notes with MBR W.Len
She has no superjump
She can infinitely dash
She cannot cancel her j.A on whiff
She doesn't have j.2C
She doesn't have 3C
She doesn't have 4B
Only hits 2 and 3 of 5B are cancellable.
5B combos into 236C
She doesn't have teleports.
Her shield bunker is horribly broken and can be combo'd off of and doesn't knock her back.
She has a very, very, very bizzare arc drive.
Her Last Arc is mostly broken. If you cancel the shield, she doesn't do it. if you let her do it, an image of her appears and she just kinda hits. It's weird.
Her 623A/B/C frame data is different than Ren's.
She has a different falling animation than Ren, and W.Len in MBAC.
She has a unique airthrow.
Her ground throw is untechable.
5C is entirely uncancellable and is also untechable. I've seen it linked to 5A, but I haven't managed to do it myself.
j.236C is HUGE DAMAGE.
I swear I have seen the ai do 236[A] like in MBAC, but I must've imagined it.