depends on your future plans, how much your budget is etc etc.
all the b series vtec heads will work, read the LS/VTEC article in the reference faqs, b20 = bored b18b
since you're gonna change the cams, i assume you'll get the valvetrain also. Just get a b16a head which should run you about 200-400 dollars for a bare head.
low budget cams: b16b/b18cR (b16b's have longer duration), skunk2 stage 1's, etc etc.