>>96339030
Depends on the faction, but rule of thumb is that old kits are better for kitbashing, they're made with kitbashing in mind. It's night and day.

Simply put: an older kit you could easily mix and assemble things. Want to try a kitbash before gluing? Dry fit or putty, you're all good.
Newer kit? You sometimes have to ASSEMBLE AND GLUE some parts BEFORE CUTTING, and that's after a lot of measuring and guesswork.

But the real kicker is: "kitbash with what?" Most kitbashes you see nowadays make use of old kits which are either OOP or will be soon enough.

TL;DR: kitbashing is braindead on life support, converting is all you have and you have to do more of it.