All of them suck IMHO because they resemble digit 8 too closely. When put next to amount, it takes a little bit of brain power to separate symbol from value:

฿485 - striked 8, still reads as 8, too busy in general
Ƀ249 - bit better as Ƀ is slightly taller than other chars
BTC853 - stands out only because it looks bolded, so sucks anyway (being an image earns three bonus sucks)

B⃦ sucks extra hard for being 2 chars (we invented new problems for you!) and not being displayed properly on my unicode friendly win7 machine, despite 64bit processor and 8gb of ram. /s

How about Bitcoin, the currency of unconditional love: ❤256