IMO, the Bridgestone A41 is a very good tyre choice for the 21/18 wheelset. Versatile.I have owned a 1090 / 1190 / 1290 - all S Models.
For road only use the S makes more sense, better wheel / tyre sizes and wider choice of tyres - nobody makes sports-touring tyres for 21" skinny rims.
If your coming off a fast sportsbike consider an 1190 - the engine is fantastic, one of the best engines I have ever sampled, the 1290 has more bottom end (sub 3-4k) but after that not much in it and the 1190 has loads of character.
The 1090 engine is way down on thrust, more so than specs imply, it matches the 1190 up to about 4k, then just as the 1190 is really taking off at 5k the 1090 has a small flat spot, giving it a peaky feel and needing a lot more cog swapping - all relative of course and if your coming from a 600cc four it will feel pretty grunty.
I had a 1090 alongside the 1190 and used it for commuting and the Mrs would borrow it for touring, preferring her TDM for local runs, I never took the 1090 out for fun with the 1190 sat there.
When I got the 1290 I sold the 1090 and would tend to take the 1190 for fun locally and the 1290 for touring, the choice of if we sold the 1090 / 1190 came down to which one the Mrs would prefer to tour on - it took her about 100 metres of riding the 1190 to make up her mid, just the first time she felt that engine do its thing. Once on tour she loved it as it made overtake so much easier for her (no need to even think about what gear you need, just open the throttle)
Don't want this to sound like a 1090 bashing, new they were cheap, and (IMHO) a much better choice than a V-Strom or that ugly Honda, and they make 30BHP more than an Africa Twin, I would alos add it handled amazingly. much better front end damping than the 1190 and I think every bit as good as the Semi-Active forks on my 1290, I still think it is the sweetest handling of the 1x90 series, partly down to great stock suspension setup, maybe also down to narrower tyres (compared to 1190 / 1290) possibly also due to containing less power - either way it was so confidence inspiring.
Build quality is good on all of them, the only exception is the 1290 plastics feel much lower quality, the rest of the cycle parts are almost identical and they are all well put together.
So, pick a 1x90 you like the look and price of and you won't regret it, just think about if you really want the R model, if your going to be on bumpy, narrow back lanes most the time it might be a great choice, less so if you want to ride faster / smoother roads or try keeping up with your mates sportsbikes in the twisties (heck, get an 1190 / 1290 and keep up with them on the straights!)
I would also say the 1190 is probably better 2-up with the smoother delivery and fatter mid-range, and the 1290 better still as the SA suspension does not pitch very much, the 1190 front end dives like an Italian Footballer - but rides bumps very well.