I'm in the same boat, wanting to switch to a single fuel for cooking. We have used a $20 Asian-store butane burner over the past 3 years and like it for its convenience, but I've decided that its too bulky (for my setup) and not good enough in cold/high altitude. After some research I feel that isobutane is the best fuel for North American travel, reasons being:
1) Canisters are less bulky than propane. Also multiple sizes available so its more versatile.
2) More expensive than propane but a lot more efficient (mostly due to stove design). In any case cooking fuel is a tiny part of the overall cost of travel unless you're a full-timer.
3) No smells or mess like liquid fuels, just connect and start cooking.
4) Great light-weight and windproof options for stoves.
5) High altitude and cold weather performance is at least comparable if not as good as propane and liquid fuels.
I've been using the 1.8L MSR Windburner which is unbeatable for boiling water. The medium-sized canister I use now (pic shows small size) lasts a REALLY long time, its basically 4 minutes or less of use per meal, and I think its good for at least 20-25 meals. Got it on sale and couldn't be happier with it.
The other "stove" I have is the Kelly Kettle. A few twigs and you're on your way to boiling a half-liter of water in about 3-4 minutes. It was an awesome piece of kit on a recent trip to India where none of the other 3 options (propane/butane/isobutane) would have worked.
Yesterday I bought the MSR Whisperlite Universal (on sale) which in theory can handle larger pots and is more stable than the Windburner. More importantly, it can run on any fuel, gas or liquid with just a jet change. I chose it over the Coleman single burner white gas stove for its ability to burn isobutane.
So the plan starting this year is to use the MSRs for North America with isobutane, and the Kelly Kettle+MSR liquid fuel for any place where gas fuels aren't available.....