It seems like most payment processors favor the buyer when settling disputes. I sell custom made software and I know that users can issue a chargeback to avoid paying. Are chargebacks something I should be concerned about? If so, are there any payment processors that don't allow chargebacks, or at least favor the seller when resolving disputes?
If you have a good product, I wouldn't worry about it. You just have to accept some amount of chargebacks as the cost of doing business. Using a provider that offers buyer protection is likely to increase your overall sales, and this should more than compensate for the small percentage of users that unethically use the chargeback mechanism to avoid paying for your product. I've used PayPal to process many thousands of transactions for access to software, and I can count on one hand the number of chargebacks that have occurred. I've also issued refunds upon request, but that is probably less than 20 times total.
Why are you so concerned about chargebacks? Surely there are other specific reasons, but off hand the only reason I can think of is if you believe your customers won't be satisfied with the product. If that's the case I'd focus on changing the product rather than the payment processor. If your product is good, I wouldn't stress out about it.