EV-Peak E4 50W 4A 2-4S LiPO easy charger
I've got this charger whose advantage is its simplicity, its metal construction and its luminous charge indicator. It charges directly through the balance plug in your LiPo battery, so there's a single connector to plug, and it's got four lights with icons that indicate the charge level at 25, 50, 75 and 100%. Its metal construction makes it much more capable than cheaper alternatives like the B3, and it's also good for 4S batteries.
The cons are that it is exclusive for LiPo batteries and that the charging current may also be limited by the balance charge cables in your battery, although the standard 22AWG wires are generally good enough for 3A, which is also the current rating of JST XH plugs. The rated 50W are consistent with charging a 3S liPo battery at 3A, but for a 4S batttery it may be power limited.
An unexpected advantage of this system of charging is that you don't need to unplug your battery from the radio to charge it. All in all, the decision very much will depend on whether it fits your use case and the price you can get it for.