I have a couple Eagletac 3400s, and I don't like them. The positive contact is barely raised at all, and seems flimsy. I have seen stories where it gets pushed in (even a half millimeter would do it) and becomes unworkable. Even if they were the same price, I'd definitely buy the Keeppower cells.
I get my cells from Illumination Supply or Mountain Electronics. Direct linking not allowed, but you can do a search easily enough. Both of those vendors are knowledgeable, and both have a presence here on CPF. Until recently (no longer selling them) IS had the SoShine 3400 (also based on the NCR18650B) and that was a better value...I picked up a number of them, and they have served me well. They still have the Keeppowers for $11.99, though, which is a good price. I haven't had any fitment problems due to the extra length.
I totally agree with your thoughts on Eagletac and KeepPower.I also find that after 1 year the E'tac were weakening[losing capacity] at a noticeably higher rate than my K'powers! The only reason I bought the E'Tac was because I needed shorter batteries for the light I was using it in.
I also agree w/the vendors. They are the Two I use. They are hard to beat for price, quality and customer service.
_______________________________________________________________________________________________________
This is a general statement and suggestion for those NOT sure which batteries to use:
I also recommend if your not sure which 18650 to get, even the ones w/ the same Panasonic cells, then please check
HKJ's "Comparator".You would be surprised that it DOES make a difference who puts these same genuine Panasonic cells together. For instance look at the difference in voltage sag b/w K'power and E'tac! Once you get to 2A there is a difference and at 5A K'power pulls away!
I was also told that Keeppower is an OEM[Original Equipment Manufacturer] and that Orbtronic is one of the manufacturers that use KeepPower. If you check out Orbtronic 18650- 2900mAh or 3100 mAh and KeepPower 18650, 2900mAh or 3100mAh you will see that the "Comparitors" voltage sag is exactly the same!
One night I literally spent a few hours comparing Dozens of 18650's! HKJ LINK Below:
http://lygte-info.dk/review/batteries2012/Common18650comparator.php