I have done Smith, Ruger and Taurus trigger work but am NOT a gunsmith by trade, lots of experience metal working though.
You will need a few basic tools such as punches, gunsmith screwdrivers, stones.
Neither Smith nor Ruger are hard to work on and smooth out quite a bit. I would not put one easier than the other if you are doing true "action work" i.e. smoothing out the internal action surfaces of the gun. Both will need to be taken apart down to the small bits and levers and put back together. The first time is the most difficult but it's not a rolex watch as long as you don't lose anything, sand / file / dremel the crud out of anything or force anything you will be fine.
There are plenty of good books, DVD's and youtube videos that go over things. Start out when you have 2-3 hours to devote to the task, take pictures prior of parts locations because you will not remember and be warry of small parts that fly out and get lost. Magnets and patience are needed if this happens or work in a box or bag to limit the direction things can go in. Don't try and do it all in one sitting and walk away when you get tired.
If you are talking a spring action job (just swapping springs) I suppose the Ruger is easier with a coil main spring one can quickly swap out for a lighter pull but to me this is not really what a trigger job is and does not produce the results that working over the internal metal does. Furthermore going to light on a main spring will result in misfires.
I also esp on stainless Ruger guns usually spend some time smoothing the trigger guard and trigger and go over the gun with some scotchbrite and then fitz to smooth out rough edges and so on. Makes a world of difference for carry / feel in the hand.
Taurus I am much less fond of working on. There is less support for doing so though their design if you have messed with other revolvers is not hard to figure out. My main problem with Taurus is the quality of the fitment and internals ones finds in them, in short on a Smith or a Ruger the gun will almost always be well fit and the parts playing with each other as they should, I am simply smoothing the finish in critical areas for better function. On the Taurus guns I have messed with it is not at all uncommon to observe that only half of an engagement surface is making contact with it's mating surface or other such poor fitting. If one alters that to try and "correct" the engagement as it was engineered to be it may well not be possible to do without new parts, welding on the old parts or with preserving the functioning of the gun or having to replace and re-fit every part of the action. Also interestingly Taurus parts tend to be either soda can soft or drill bit hard. Makes for an interesting time trying to work on them. Every time I mess with one, or other Brazilian made guns I say never again, then get talked into or given the gun and then give it a whirl and I do always learn something in the process.