Glass clearomisers may be your thing if you want to avoid plastic. (You may also want to look for e-juice in glass bottles.)
Now, these ones here are all bottom coil. They provide more vapor but less throat hit in general. And that is true. However, I didn't have unsatisfactory throat hit and am quite happy with vapor.
So, after months of using all kinds of plastic clearomizers, I almost completely switched to these.
Another good thing about them - both have their mini-versions intended for popular eGo size batteries.
Kanger Protank 2 and Davide clearomizers are made without any glue whatsoever.
With tank body made of Pyrex, a low-thermal-expansion glass, they don't cause problems with acidic flavors unlike plastic clearos.
Good news is also that Davides, Kanger Protanks 1 & 2 and Evods use same coil heads which can be purchased in 5pack for less than 10$. Plus each of these clearos comes with 2 or 3 (Davide) additional coil heads, so you are all set for ages like I am. Evod also uses the same.
Last but not least (not for me anyway) glass clearomizers look much, much better than plastic ones. I've had my share of CE4 and myriad versions of CE5, ViVi Novas, cc510, am also using T4s and Vision Nano (little clearomizers with pretty good performance) and find my glass clearomizers more esthetically pleasing.
They have this sleek look that no plastic clearomizer can ever have, especially if it comes with long wicks.
A warning: (just in case you get impatient and too anxious to try your bottom coil glass clearomizer the very moment yoou see it) make sure you take a look at the short and concise manual that comes with each. It will tell you the exact resistances of your separate coil heads and recommend the corresponding voltage to set your battery to. Keep within the recommended limits. Otherwise you may burn your coil head. Not a disaster, you still have others to use, but why not learning from my mistakesJ.
With all that said, someone who values throat hit above everything else might find the experience with a bottom coil clearomizer somewhat disappointing. However, you should at least give it a try because of all the benefits listed.
Kanger Protank 2 can be taken apart completely and all its parts are replaceable, whereas in previous version you could only unscrew the bottom to refill and change the coil head. Your clumsy reviewer has had both of them roll off her desk and table hitting the floor hard several times. Nothing happened, so this is a huge plus in my book.
I haven't tried Kanger Protank Mini, but my guess is that isn't much different from Mini Davide. Generally, I found only minor differences between these two brands of clearomizers. Find them at Apollo by clicking the banner below that summarizes their main features.
UPDATE 2015: Kanger Protank 1 has been discontinued, but if you search through the pages in the link, you can still find Kanger Protank 2 and Mini. Also Kanger Protank 2 is now a part of many starter kits like Apollo Valiant Kit.
Anyvape Davide Mini Glassomizer is the one I'm using with my Apollo eGo VV and you must admit it looks really good. It has a nice output of vapor, decent throat hit. Besides its mouthpiece is probably the best one I've come across – shaped to fit your mouth, top to bottom. Try and you'll see what I'm talking about.
The only thing I didn't like about this Mini was the filling procedure – its three holes require either pointed top bottle or syringe.
Beside Mini, there's Davide Standard in the same size as Kanger Protank. These Clearos resemble each other, only Davide has more rounded design. In UK and US, you can buy them at Apollo.
UPDATE 2015: Davide Mini is nowhere to be found. However there is Davide Standard (3 ml) and this is the direct link to Apollo US site. The banner below leads you to Apollo clearomizer page.