SkyRC MC3000 - non-intuitive control, overloaded screen, many rarely used settings, no support 21700 protected
Upgrade MiBoxer C4-12 - lack of measurement method capacity by the method of discharge, a bulky power supply
Xtar VP4 Plus Dragon - no support for: LiFePO4, Li 4.35, 21700 protected
Liitokala Lii-500 - no support for: LiFePO4, Li 4.35, 21700 protected. Disgusting measurement of the internal resistance of the battery
There is not one perfect charger. I have a gryfalcon 88 for charging every kind of cell I have (NiMh, LiFePo, 4.2V, 4.3V and 4.35V, don’t know if it can accommodate XX700 cells) and an opus for testing my cells. I never bought into the SkyRC after reading about the poor hardware construction. I don’t see any point in paying for great software packaged in cheap easy to break plastic period. I also have a hobbycharger for charging powertool batteries and LiPo bateries with cells in series.
I have a few chargers that do different things.
I am not aware of a perfect one. I would be thrilled with a decent 2-port charger that measures capacity and I could give to a friend without risk. I would buy a few of them.
Accurate measurement of battery internal resistance requires a different method than the one employed by analyzing chargers. Internal resistance of a cell is in the same order of magnitude as rail contact resistances and such. The fact you may see a more or less matching figure in a charger's screen does not make it accurate, it is due to a combination of errors.
I find the internal resistance measurement useful to determine if a cell is well seated in the rail, which happens when the measured value hovers at a minimum. Just that.
I have Seven different brands[KP/Nitecore/Folomov/Fenix/Efest ect.] of chargers and without question my Opus BT-C3100 2.2 is my favorite! 
iirc the VP4 dragon plus use 4 wires method to measure IR, so it has the best accuracy
I think it in reverse. The SkyRC MC3000 at least have ridiculous software, but good hardware. Mostly. The 1A discharge maximum if you use more than one LiIon battery is a shame. Also, the 4th channel looks weird recently, the voltage measurement provides very strange data, at least with LiIon cells. I will have to double check it.
My main charger is Miboxer C8. Intelligently sets the charging rate, 1.5A for the bigger cells, lower more appropriate charge rate for smaller cells 14500, 18350. Only downside is it will reduce charge rate if high resistance so some 26650’s will only get 0.6A but there is a manual override.
Lii-500 secondary to measure capacity.
My first was Lii-402 then Xtar VC4 but these don’t come out of the box much anymore.
I personally prefer my chargers to just be good chargers and don’t need analysing functions. If I want to measure internal resistance or capacity, I prefer to use separate hardware (e.g. a purpose built battery tester). As a result, I really like the Enova Gyrfalcon All-44 and All-88 as they can charge just about any type of battery, have 4 different charge rates (0.1A, 0.25A, 0.5A and 1A), and can charge all bays at 1A simultaneously. Sure, it could have a faster maximum charging rate, but I like 1A max as a reasonable rate that maintains better cells health than charging at a higher rate. There are also individual displays for each slot that always show charing rate, charging time and current cell voltage. For me, the All-44 and All-88 are just about perfect general purpose chargers. Only change I might make is for the bays to be slightly longer to be able to fit protected 20700/21700 cells (unprotected ones fit fine), but the chargers were released before these cell sizes started to become popular, so I can forgive it.
I was thinking the same thing. I took it apart and it is great build quality for a great price. But I agree the software could be worked on.
I’d love a single charger that:
- can handle cells from 10180 to 26980 and 32700 (and charges each with sensible current)
- can measure capacity and internal resistance with fair precision
- has configurable termination voltage, both for charging and discharging (for the sake of capacity measurement
- can charge or discharge batteries to storage voltage
- can work with at least 2 cells at the time
ISDT SC-608 is close but still not it.
I would take Xtar VP4 Plus Dragon for the base and add to it the possibilities of Miboxer C4-12 - charge in any slot from 0.1 to 3A with the possibility of manual selection. I would also add LiFePO4 chemistry and Li 4.35. I made 2 power inputs - from 12V power supply unit and PD 2.0 Type C. Also I would change the screen so that information on 4 slots was displayed simultaneously. A price from $ 70 to $ 90 would be justified.
Thinking some more about my dream charger…
Main features:
- charging
- discharging
- putting in storage mode
- testing
- maybe also
- powerbank
Physical layout:
- ISDT-like display with rich UI (so you can have extensive configuration without 23-clicks)
- 4 bay, supporting 10440-21750 or 10440-26650 (not sure)
- the 2 outer bays support up to 32650
- included spacers allow you to charge 10180 or maybe even smaller cells
- standard LiPo charging/balancing sockets
- probes for 4-terminal IR measurements
- maybe also
- USB Type A and Type C (with USB PD support)
- DC barrell socket
Charging features:
- supports all chemistries
- automatically determines charging current based on IR measurement
- but lets you override the decision
- configurable termination voltage
- supports currents as low as 50 mA and as high as reasonably possible.
Testing features:
- configurable termination voltages
- configurable discharge current
Powerbank / power conversion (if supported):
- any port can be input or output, so
- it can discharge one cell to charge another
- it can take power from DC and output Type C
- it can take power from Type C and output DC (with configurable voltage)
- it can take power from car 12V socket and charge cells
Liitokala Lii S1 is my perfect charger. It does everything I wanted.
I have several Xtars I like.
Lii500 I like.
Lii500S on the way, I’ll probably like it too
Lii100’s I like
Lii 202’s I like
Opus BT-C3100 2.2 I like OK
A few other brands that are fair too
I also have a SkyRC, but sadly; it is smarter than I am. 
. 
I have:
Lii-402 i like
Xtar VC2S like but not very
Miboxer Upgrade C4-12 on the way
Hmm, that looks interesting to me.
Back in the day, my Powerex C9000 was the go-to charger for NiMH and NiCad AAA and AA cells. I have one and use it all the time; it shows all sorts of data like charge and discharge rates, cell capacity (upon discharge), amount of charge accepted, etc. I even bought some adaptors that let me charge up to two D cells at a time, at up to 2AH. The C9000 also has a ‘break-in mode’ which creates a good forming charge in a cell that’s been sitting for a long time, and a ‘refresh & analyze mode’ that will charge, discharge, and recharge automatically and tell me the cell’s capacity in the process.
If the Opus shows data like that for Li-Ion cells, I might have to get one. My Gyrfalconis pretty well-featured, but it doesn’t show me the data I’d like.
Both the Opus & the Lii500 show data/are analyzing chargers. There may be others, I am familiar with these two.
The SkyRC MC3000 does also.