IMHO, there is no good reason (beyond bonuses) for a sole proprietor with a small business to get a biz card. In fact, can be dangerous since biz cards are not protected by Fair Credit Billing Act. Better to use a personal card for biz purposes.
Right now, I would apply for an INK Bold from Chase (biz card, but 50K bonus for $5K spend in 3 months makes it worthwhile, until spend is met, then go to personal card).
Also, personal Chase Sapphire Preferred with 50K bonus for $3K spend in 3 months.
Of course, you will find many more on FT and the blogs but those two are a good start.
Keep in mind that unless you are spending really, really big bucks the bonuses are where the miles are.
