We use one of these
http://www.amazon.com/HiTec-44169-4-...=hitec+charger as our primary charger/maintainer with a couple of the KOP ones as backups.
It has four really nice displays (one for each battery) that tells you the current voltage and charging amperage. It also has some "PC link" features that allow you to access charging data on a computer but we have not taken advantage of that feature as of now.
That particular model requires you purchase an external PSU but there is a more expensive one that comes with one built in. We chose to get our own cheap power supply but I would recommend against it because its became a pretty big hassle (we needed to add fans to cool the PSU, etc...).