This has been heavily discussed on specialty-coffee forum and also barrista guild.
There are several high end systems that will set you back a bunch, Aloha and the like.
For smaller operations, I am down to 4.
Coffee Shop Manager - CSM. Great reviews, most expensive of this group of 4, at about $1400 per license. License provides a back office lic as well. Addl machines are less. CSM offers packages with hardware, and they include programming your menu (if you buy the package). I have found that I can save about 50% off of their lowest package ($4900 w/ hardware), if I am willing to do the programming and buy my hardware. Performancewise, CSM seems to be great and gets great reviews. They also charge $300 for annual service contract that includes technical support and upgrades. Interactive demo availalbe, no download.
NextPOS - closest thing that I have seen to CSM. $750 per copy, addl copies go down in price by $50 each to about $600. Distributed through resellers who want to sell you a terminal system. Packages avaialable. You will need to purchase an extra copy for backoffice if you want a back office computer (I recommend this, as you don't want to be looking at your data while your trying to use the register). NextPOS is feature rich and has a fairly simple interface. You can purchase menu programming services from the resellers. Trial download available
Denver Research - I have heard good and I have heard bad. This software is more of a shareware type product and is marketed through shareware sites. Not as glossy as the first two, but certainly cheaper at $300 per copy. Trial download available.
Business Plus Accounting from Businessoftware. Cheapest of the bunch, sort of. $70 per copy, and it is a sitewide license, unlimited terminals for your location. They do want $30 per month for service adn free upgrades. Based on Foxpro, it seems to have most of the desired features, though somewhat a cumbersome interface from the operations perspective. The register interface is adequate. Trial download available. This software also advertises a full capability accouting program, including payroll. It can export to Quickbooks, but does advertise as an all in one.
CSM and Next POS can control webcams and record shots for refunds, voids, etc.. Don't know about the other two. Export to quicken seems to be better enabled for NextPOS and CSM.
If total ease of use is what you are after, I would go wtih CSM or Next POS. If lowest cost is what you are after and don't mind some work up front, perhaps BPA is the way to go.
Any POS system will require you to keep accurate records and track your waste. They will also require that you program your menu down to the ingredients. This allows them to track stock accurately, and costs. The more tracking your system is capable of, the more rigorous you have to be on documenting your transactions and activities. Knowledge comes at a price.
Charlie