I don't know about being the best, but they're definitely some of the most expensive! You don't need to spend that much money to keep your batteries in good shape.
I see chargers as falling into 4 general classes.
The simplest and cheapest are the slow chargers. Often these don't even have a timer to shutoff. Plug in the batteries and let them charge 14+ hours.
The most common fast chargers have 2.8VDC outputs and charge two batteries in series. OK if the two batteries are well matched, and are equally discharged. But if you put a discharged battery in with a battery that has lots of charge left, the battery charger will overcharge one battery and undercharge the other. You can tell this type of charger by noting that the voltage output is 2.8V and the number of outputs is 1/2 the maximum number of batteries that can be charged. If you use batteries in pairs or banks of 4, then this charger will do a reasonable job.
A good quality charger will individually charge and monitor each battery. If you look carefully you can find this type of charger for reasonable prices. It may be difficult to differentiate this type from the 2-at-a-time charger. The fine print on the unit will show the output voltage as 1.4VDC, and the number of outputs is the same as the maximum number of batteries that can be charged at one time. This charger just charges the batteries, and terminates the charging based upon time and changes in the battery voltage. This is my preferred charger. Typical examples are Panasonic BQ 391 ( 1 to 4 cells) and BQ321 (1 or 2 cells).
There are also a number of "smart" chargers with extra features such as the ability to measure capacity, the ability to discharge a battery before charge, etc.
Although many prefer to spend the extra bucks for these sort of features, I find that a simple voltage check with a DMM will tell me everything I need to know. If you are a gadget freak, then definitely get one of the smart chargers. If you just want to charge your batteries and keep the scanner running, then I suggest the simple, cheap charger that charges and monitors each cell individually.