As others have said - the phrase “best bass” is to subjective to have much relevance. In general Carvin & now Kiesel basses are well made and are an excellent value on the used market. The new prices are fair, considering they are US made and use top quality hardware & components, and they allow an extensive level of customization.
I have two - an older B4 - similar to the LB70 but more of a jazz clone. Bought it used of CL, one piece solid Koa body, ebony FB, quartersawn maple neck & it came with the OEM tweed hardcase made by G&G cases. Thats a bargain at $500.
Just picked up a Kiesel vader 4. Like it so far but the jury will be out until I’ve lived with it for 6 months or so. First step is to restring it with flats.