To debrief - exfoliating toners are those that contain chemical, natural enzymes, etc. (no peach kernels here). You know the whole exfoliating acid craze, so, most often, they contain glycolic, salicylic, lactic, and other sorts. Not only do their buffing powers, literally buff to reveal brighter and newer skin underneath, but they also increase cell turnover, and, the key factor, lower your skin's pH. I'll try not to get too chemistry class on you, but the lower your skin's pH, the more bacteria fighting, spot ridding, and better it will look.
Previously, my toner crush was the Clarins Gentle Exfoliator Toner, but the fact that it's pretty darn expensive and a pain in the bum to get in the US means that it was time for a breakup. Alas, rather quickly, I've gotten involved with the REN Clarifying Toning Lotion.
If I were to compare it to its Clarins alternate, I'd say that they're very similar. Their effectiveness? Nearly identical. I'd say the way they differ is in the texture. The Clarins is a much more wet, lotion like consistency. It only takes a little bit to wet the cotton pad, and, let alone cover your whole fact. In turn, you may need to wait a while before you carry on with the rest of your routine to give the toner a chance to dry and so your hands won't feel like they're swimming in product. The REN, on the other hand, is a much dryer consistency and I feel like I have to dump a bit more on the cotton pad to paint my visage. Nevertheless, the REN option is definitely better value for money (always what we're looking out for these days) and I find it is a bit more convenient considering you can slap and dash with the rest of your routine.
The Clarifying Toner is part of REN's range for combination skin, but I don't think that this should scare anyone with dry, oily, or (dare I say) mature skin, as I think that it doesn't really matter what kind of skin you have - everyone could use this. If you've got sensitive skin, I think that it would be fine, just use rarely and work your way up to a more regular application.
As for ingredients, you know this is why I loovvveee REN skincare, it consists of lavender and peppermint water, bergamot extract, willow bark extract, lactic acid, lemon and pineapple extracts, and glycolic, lactic, citric, and tartaric acids.
I use this toner day in and day out - night and day, but this may not work for everyone. Just conduct your own little experiment and figure out what works for you. Although I do use it pretty often, I've rid my routine of any other exfoliating treatments, as I find that I don't need them anymore and they, instead, reck havoc on my skin.
So, to generalize, if you haven't tried an exfoliating toner, pick up some samples and get trialling! Then again, you know how qualified I am, so I only speak from personal experience. Regard with caution, but you won't need gloves to apply the acids.