Basic No-Blush Epoxy
I've been using Basic No-Blush epoxy from Progressive Epoxy for some time. It's unique in that it has no amine blush. This makes it much easier to work with than many other brands. I've used it in a wide range of temperatures, down to 50 F. with great results.
The best thing about this epoxy is day after sanding and with no amine blush, your sandpaper won't clog. This will save you many hours of frustration and no more wondering if the epoxy is ready to sand. The mix is an easy 2:1 and it's very forgiving. I've never had a batch not cure even when I've lost count while mixing.
Warning - While this may be the BEST epoxy out there, Progressive Epoxy may have one of the most confusing web sites. If you are patient though you'll find all kinds of interesting things on the site. Paul Oman (Progressive Epoxy owner) is a boat builder and frequent contributor to the rec.boats.building newsgroup. He answers his email and I've appreciated his help on my projects.