I've grown to using Taramet Sterling exclusively.
It's a lead-free and has a pretty wide pasty range. It doesn't seem to heat up as quick as others, but it is very forgiving and makes a very good looking joint.
The main reason I use it, is that I have no worries when soldering bigger pipe, 2"+. The solder will give a nice 'fillet' around the fitting. With 95/5 solders, like dutch-boy, oatey and super 50, I find the solder pools at the bottom of the (horizontal) fittings. All it took was a weeping 1 1/2" line to get me to find something better.
The Taramet also gives the feel of a bit of 'resistance' when applied to a heated joint. This helps a ton when you can't see the back of a fitting, you can feel the joint through the solder.
It's a bit more expensive, but much more predictable. If you do any work on larger, 1"+ stuff, try it. You'll never buy anything else.