Deffinetly Horizontal business cards… With minimum details on front , just name and phone , rest on the back … Also i love dark ones with live colors …
I think you have to be careful with whbat type of business card you associate with what type of business…
Are we talking about :
Planet Express under the management of “that guy”
SimpleBits design firm
Law offices of Conservative and Serious
get my point?
My views as a receiver/storer of business cards.
I store business cards in a “book” that has transparent plastic sleeves (pages) that open horizontally. I usually store two cards per sleeve - back to back.
The reason I store the cards is to easily find the contact information of the person I wish to contact.
So, the best business cards I have received have the following attributes:
- Clear, easy to find contact information
- Nothing important on the back (I can’t see the back without pulling the card out)
- Are horizontal so I don’t need to turn the book to read them.
- Have black text on a white background for ease of reading
- Is a standard size which fits in the sleeve pocket
- Has a clear, good sized font for the phone number (at least) so I can read it easily while dialing.
Flipping through my card book, I find the worst cards are the ones with graphic backgrounds and the best one (the one I find easiest to read while providing best information) has a colored sidebar on the left (about 1/4 of card width) containing a logo and what the company does (one word for each service they provide), then the remaining section has everything centered - company name at top, person’s name middle and contact information bottom.
One I came across is interesting. It has a b&w photo of the person on it. This could be something to consider as it certainly helps me remember this guy and adds another dimension - it reminds me of what he is like and triggers memories of previous interactions.
So, if you can make a good impression in person, having your photo on the card may trigger memories like, “I remember that guy, he was fun.” or “I remember her professionalism.” or “Oh yeah, he was a pain in the ***.” 
Kevin Mitnick’s business card:
http://farm1.static.flickr.com/48/106709219_6c8be9703b.jpg?v=0
again, if you’re a law firm, you shouldn’t be advertising yourself like a former hacker felon.
I think horizontal cards are standard for people. They are used to seeing Business cards in this format. Although I do agree that the vertical card looks interesting and that could make it more memorable. But I also think that your business card should be most helpful for getting your contact information than for keeping you in mind. People usually remember whose services might be useful at a later time. If you have spoken with a possible client and given him your business card, he remembers that you can do a certain service and what he needs is your phone number or e-mail for contact.