I've never raised banty Brahmas but I've raised standard Brahmas and very similar breeds of Bantams so I'll try to give you a run down of likely pros and cons
Bantams, Pros:
- Less feed
- Less space
- Easier to handle (cute lil lap chickens)
Bantams, Cons:
- Smaller and likely fewer eggs
- Harder to source
- Can't purchase sexed unless you can find older juveniles/adults for sale
Standards, Pros:
- More and much larger eggs
- Easier to find
- Can be sexed as day olds
Standards, Cons:
- More feed
- More space
- Harder to handle (similar personalities to banties, but those big birds can give you some good wing-slaps if they're startled!)