I have both the Energy CB-20's and Sony CS5's. Both are good speakers for their price points. The CB-20's do require a lengthy break-in period, but once they are settled in they have a really nice, balanced sound. For 6.5" woofers the cabinet size is relatively small, coming in around the size of most speakers with 5.25" woofers. I'm using the Energy CB-20's with the CC-10 center in my very small theater room set up and I've been very pleased with them. Aesthetically speaking, the Energy speakers look a bit more stylish. Both speakers benefit greatly from a sub to anchor the low end, but the CS5's are a bit thin in bass on their own, more so than the CB-20's. IMO, both are edged out by the Polk Signature speakers, which generally cost a bit more.
Subs>RBH I-12e/I-12. HSU VTF-15H mk2. Monolith THX 12(x2)/THX 10(x2). XTZ 1X12. SVS PB-1000(x2). Speakers>JBL Studio 530/520c, 270/235c/230/225c, Arena 130/125c. Jamo S807/S803. Pioneer FS52/BS22A/C22. Sony CS3/CS8/CS5. QA 3020i/3090Ci, 2020i/2000c. Monolith AM Cinema 5 bs. Polk RTiA1/CsiA4. Infinity R152. Other Audio>Sony MDR-Z7m2, WH-XB700, XB32, XB31.RBH EP1. Logitech GPro HS. Plantronics RIG 500 Pro HS. LG FH6,RK8,PK5,PH4. UE Boom3.