Stihl Easy2Start works excellent, but the largest saw you'll find it on is the 250. I like my 250, but it is a small saw (45cc/3.1hp) and many people here has not yet seen the light on this one... With Easy2Start you can pull as slow and short as you like since it's just like winding a spring. When it has reached enough tension it releases and starts the saw. If you need both hands to hold your saw you could actually pull the handle with your teeth, it's that smooth.
Elastostart does not make it easier, as in less resistance, to start the saw, but will make pulling it a lot smoother since it in practice is a piece of elastic rubber that connects the pull handle to the pull cord. Every saw of every make should have this...
Husqvarna has a new system on their e-series that I have tried on a string trimmer. It still requires you to pull rather snappy and at some speed, but then immediately does some magic to make pulling amazingly effortless, almost like if there was that old automatic decompression valve again. Works well, and my 78-year old mother loves it, but I have no idea of how it works.
The Husqvarna 455 Rancher tool-less has this and is a bit larger than the Stihl 250. You won't see that Husky being recommended that often on this forum, but in this case it might be a saw to consider. It's simply the largest saw he can get with any kind of starting assistance.