I own all 3 torches now!
My perfect torch would add a charger input port to the LC40. I'd also like a combined charging in and out of merging the Powercore+ mini power in+out with the LC90's power in with the LC40's size. I know this merges engineering challenges for Anker but really "one device" which acts as a torch, you can recharge it off USB and it can recharge your phone. You can then choose do you carry lots of potential spare light or drain the light with recharging your phone.
The example problem I have coming up is I'm traveling a lot in June and I don't expect to need a torch at all / much as its daylight til I expect to be in bed anyways, but I'm also hiking in mountains so its a "just in case" torch need if I'm lost, etc. I could add a headtorch or I could just use the torch off my cellphone but then hiking and walking with a phone ahead you can drop / break isn't wise. I'd probably be more likely needing to top-up my phone. So what do I do? Well I'm thinking I'd carry the LC40 plus something like the Powercore 10000 plus a spare 18650B in case I either deliberately or accidentally drain the LC40's internal battery and I can't recharge it.
The LC90 is water resistant and to recharge it is unscrew the button section, it would be good if that revealed an output port. The LC40 form factor is a good size, LC90 with more CREE and the focus is wider. The LC130 is more waterproof.
The torches in USB batteries are usually feeble, more "Find your keys" type.