If you get a chance to have a play with them then definitely do that as your opinion on what is a good one will of course vary from mine. The ones I've used seem to be pretty much of a muchness, but my preference is for one where the handle flares out, rather than straight up and down.

Something like this one but not necessarily this brand.

Rebel Sport 16kg

A grippy handle is essential (don't want the kb flying away whilst doing those 2 arm Russian swings hahaha) so a firm rubber coating is what I like.

Interesting I was leading towards the basic cast iron ones because they looked more 'russian' - http://xtremefit.co.nz/cast-iron-kettlebell-3-per-kg/

I brought mine (along with a whole bunch of other stuff) from http://www.industrialathletic.com/products/category/40/kettlebells

They have both the standard cast iron and the pro-grade which are used in competition. Personally, I use cast iron but i also use chalk so no worries about slipping.

Thanks - most of the use will be in my work office. Chalk is a bit messy for that. I assume you could use them safely without chalk.

Or grab a roll of grip-tape from Rebel (or wherever). Has the added advantage of customizing the weights a bit so you don't get them mixed up with everyone else's.

I purchased a 20kg one from no1fitness

Good quality, and feels good holding with two hands.