I personally think that Square is the best. I have used it since shortly after it came out (almost 3 years) and their service has only gotten better and more efficient. Here are the advantages I think they have:
**The money goes straight into my bank account - all in one lump sum (per day) and for shows that I do on a Saturday the funds are in my account on Monday afternoon. And if I do a show that is Saturday and Sunday - there are two deposits - money from Saturday, money from Sunday and both are available by Monday afternoon.
**I don't have to mess with transferring money from a Paypal account over to my regular account so that I can use it.
** When I noticed that my card reader was not working, I went online to order a new one - it came in the mail within 3 days - no charge.
But always have a back up to technology - in the three years of doing shows I have had two experiences where I was unable to use square - no wifi and no 3G access - I was in a large building and there was no signal. So I STONGLY recommend that you also have the "old fashioned" knuckle buster card machine to process credit cards. If I had not had the old style machine - I would have lost several hundred dollars worth of sales. And you can order a knuckle buster online for about $20-25 - which comes with the custom imprint plate (has my business name and info) and 100 carbon copy receipts for the machine. It is always a good idea to be prepared for the times when technology does not work!!
And in the case where I used the knuckle buster - I just explained to the customer that I was unable to access Square, that I was going to process the card the old fashioned way, then when I got home I got into my square account, processed the sales and then emailed the customer a receipt. Just be aware of what information you will need if you are going to be keying in the card number instead of swipeing - you will need card number, expiration date, 3 digit code on back of card, customer's zip code and an email if they want to receive a receipt.