HKJ in his wonderfull reviews says that the i2 is better than the i4.
i2 is a good choice, I have it and no problem, even with AAA nimh.
they also don’t seem to charge to 4.2V, one i have goes to 4.11v and the other 4.05V
The ones I used as gifts all went to 4.18 which is fine IMV.
I have a ML-101 that I chuck in a bag when I travel light (sorry!). Out the box (like the 102), it has to be modded for longer cells but that is easy. But I have no concerns about how it charges, which it does well and its safety.
This is an inaccurate statement ...SLOW is not a correct charger .
It almost never was even a very long time ago in nicad / nimh days
termination and correctly charging is 100 times more important ..
slow is actaully a bad charger
i can’t agree, i know we will never change each other’s minds but i want to point out this is not a settled issue
I have two ML-102 v5 and would recommend them. They’re really straightforward to use. Termination voltage is 4.2V, accuracy ±1% (mine 4.15V and 4.2V). I generally power from a USB wall supply because its quicker (900mA vs 500mA).
Can you suggest a good place to purchase from?
FastTech or Intl-Outdoor both have v5.
http://www.fasttech.com/products/0/10001919/1137904-miller-ml-102-universal-usb-smart-charger-version
http://www.intl-outdoor.com/ml102-usery-p-243.html
Oh, these v5 have micro USB sockets (mine have mini USB). I wonder if anything else has changed (protected cells don’t fit in v5).
Ah that’s a shame, no good for me 
The ml-102 like this one the ml-101 is very easy to mod to take the longer batteries.
Did you cut the two plastic guides for the v5 leaf spring?
I have a USB power adapter rated at 500mA. If I connect to the ML-102, can I use it to charge 16340/14500 with spacers?
Yup you cut the two ‘guides’ flush, there is a divider that stops the leaf spring touching the led wires, I cut it in the shape of the spring cutout. I think you could just hinge it if you would prefer, but not tried it. I put heat shrink on the led wires to protect them.
Where the leaf spring bends over at the top I cut it. How long one leaves it, is down to preference and experiment. On the ones I did the spring was doubled so I removed one leaf. I ran a small bead of hot melt (could have used araldite) on the top back of the leaf so if it ever did bend far enough to touch the heat shrink of the led, would give it a bit of cushion.
Lastly soldered a copper spring (from FT) thin end onto the leaf. Then modded the opening (mostly the bottom cutout), so it goes through, I make it so the wide end of the spring just binds with one coil on the back opening to prevent too much rearward travel, but again the opening could be make bigger so that did not happen
This pic should give a better idea of the finished product, For myself I go with function over form so I just hacked it with a stanley. But the ones I gave away used a dremel and needle files and you had to have a proper look to see it was not stock. More difficult to describe than to do 
The best point ever!
And you mentioned a two-pack, which puts the battery cost alone above $20. To me, that puts all these chargers in the “cheap” category, especially if your friends ever wear out that $20 worth of batteries…
It had better be! 
(I know you’re eating the entire acquisition cost, which is most of the TCO. Your friends only buy the electricity for recharging. Still, the Total Cost of Gift (TCG) (if it helps to look at it that way) diminishes to nearly infinitesimal, and that right soon. Sorry if that’s OT…)
If it is a regulated PSU it should be okay, might get a little warm.
For smaller cells like 14500 I prefer to charge at 500mA (and lower). My laptops are capable of supplying the higher draw (~850mA) so I tricked my ML-102 into charging at the lower current by using a cheap USB hub. ‘Charger Doctor’ shows the draw through the hub, multimeter shows the charging current:
I have two of these ML-103 V2.0 chargers from Customlites.com.
Comes with 1A wall supply (USB output), USB to DC power cable, and charger base. Charger has no USB input or output connectors like some similar models, only DC power input jack.
Both of mine seem to charge consistently to 4.18-4.19 V.
Has coil spring at neg batt end, so I think protected cells should fit OK (I use unprotected cells).
$8.99 usd +shipping
I’m quite happy with these chargers so far…
JW
MC1. Basic single cell .5A charger. $5us Great for giveaways.
Termination on my unit is 4.22xx to 4.20xx (±.05) accuracy. My i4, $19us, 4.18xx to 4.202x for my sample.
As far as speed goes, I prefer slow charge, as this gave me more runtime on my heli LiPo. Fast charging gave shorter runtime, always. We are talking 35C dumps, 4 minutes, during flight with now hot batteries and controller at end of flight.
For flashlights, everyone seems to want 2 minute recharge. iCharger reports lower capacity when charging at 1A (max on sony laptop pull) vs .5A.
What do you guys see when using hobby charger?
i2 my go-to cheap charger. It can be had for $10 with shipping. i4 if you need more cells, but if it’s a gift for someone new, I would go i2.