Zombilazoricious. They can be fun, for sure, either as very mobile XL vomits or as ultra durable (for the weight) lazer platforms.
Choose the Quirks you like, they are quite similar I would say: CRB-27SL: XL250 and JJ, must get. CRB-27B have 6 energy hardpoints. CRB-20: have a higher engine cap. CRB-27: 2x AMS. 27SL for sure, then 27B, the other one is a matter of taste. (Roaches build)