I can highly recommend this Anita sports bra - I am a 32F (which may be too much information to share on here!) so I know your pain for finding good bras. It is fantastic for aikido (and jogging). Here is a link to a pic in white - this is on an Australian site but you can buy on US sites too.
It has a really good mesh back and is very comfortable. It is a soft cup so no wires to poke in. I don't notice it at all when I am training and it has washed and worn very well given it gets a pretty good going over from me thumping on the mats. It's expensive but worth it!