ThunderPower makes good stuff. I use their batteries and I’m quite happy with them.
That first charger that Vince linked to is rated at 80 watts. Every time I charge for a day of flying I more than double that.
The single unit John shared with us is a 100 watt unit. Still not enough for 4x4S 2800 to charge at 1C.
The 4 channel unit claims 4x100 watts, and that would do the job. It has the added advantage of charging/ discharging batteries individually, as opposed to my setup using a parallel board to do one process to four (up to six) batteries at a time.
My charging setup is way overkill for what I need. I started with a junk charger, got an iCharger 106B which was good, but it failed. I fixed it, it later failed again. Then I got a PL8 and an MPA parallel board. I love this setup, and it has plenty of power. Well, later on I ran across a smokin’ deal on another PL8, so now I have two along with two MPA boards. I have them installed in a pelican case along with a power supply. Can also plug them into the truck for charging at the field.
You say you’re going to eventually fly .60 size stunters. That will take more power, aka bigger batteries.
Buy the charger that can handle your future needs, not just what you need now. Two or three upgrades later you will have spent more than if you ‘go for broke’ now.
If I had to choose from those three, it would be the 4 channel unit. For a little more money you can get a PowerLab 6 and a parallel board and have 3 times the watts. But, it requires an external power source.