Ok, from what I understand there are only 4 Mexoryl sunscreens available in the US market - the LRP, Loreal, Lancome, and Kiehl's, and all are made by Loreal anyway. The active ingredients in all of them are pretty much identical (with the exception of the Lancome and the Kiehl's SPF 20 version which both have titianium dioxide to up the SPF and make it water resistant). But I decided to go with the Kiehl's because, as the other reviewer points out, it is cheaper! Unless you have some sort of coupon for the LRP or Loreal, Kiehl's is by far the best value - the Loreal one is actually the most expensive! This goes for $29.50 for 3.4 oz.
Ok, now for the product itself - I wanted something with good UVA protection, and wanted to be able to buy from a physical store, so this was really the best option. There isn't a fragrance in this, and it is pretty moisturizing. I just put on my serum, then this and let dry before applying my foundation. It feels pretty greasy when you first put it on, but it soaks in pretty well after a few minutes. I've worn this out in the sun several times, and haven't noticed any change in color, so I suspect that even though it is a lower SPF, it is giving me pretty good protection. The only thing is it is a bit creamy to wear right around the eyes and it sometimes travels into my eyes and makes my contacts blurry, so I use a separate eye sunscreen.
I have oily skin with acne, and I use differin, so I need some decent protection. This hasn't caused me any problems with clogged pores as far as I can tell.
So if you are looking for a mexoryl sunscreen available in the US, in my opinion this is your best option for price and availability. (I'm lucky enough to have 2 Kiehl's counters and one Kiehl's store within a mile of me, so I can pick some up any time I want).

KIEHL'S UV PROTECTIVE Everyday Facial Moisturizing Sunscreen Cream SPF 15 w/Mexoryl: There are a whole lotta words on this tube and not really clear which ones are the actual product name.
This is one of the newer sunscreens added to the Kiehl's lineup in Fall 2007, and is one of the few US sunscreens with Mexoryl (one of the few good things to come of L'oreal's acquisition of Kiehl's).
While all the MUA hoopla focused on L'Oreal's Revitalift UV, this Kiehl's version is more cosmetically elegant, better packaged and (gasp!) cheaper than the L'Oreal at retail. The Kiehl's reminds me a lot of La Roche Posay's Mexoryln sunscreens. It's a fairly thin, milky-ish lotion more than a cream. Unlike the L'Oreal, which has a faint French Lady Perfume scent, the Kiehl's has no noticeable fragrance, just a faint sunscreen smell.
Avobenzone 2%, Ecamsule (Mexoryl SX) 2%, Octocrylene 10%
Cost: $25 for 3.4 oz.