I like the service real-pcb.
The reason I would suggest them is because of their policy of doing panelization for free. This really helped me because I use EaglePCB and it has a size limit, so I can't panelize myself.
So if you (like me) have several projects going, or various self etch or utility boards that you would like to have (SMD adapters, transformer adapters, PSU boards and the like), then you can do one run and get several different cards made. Overall price is a full run, but the value is quite good if you have need of various cards.
They did "routing with tabs" separation for me because I had some shapes, but they may do scoring for square cards. When they did the tabs they did the little holes to make the cards break out easily.