KHL has a higher high end, but lower low end than the SHL. So it depends on what you prefer.
The best talent outside of North America is commonly in the KHL. SHL, Liiga, Czechia, etc. have some top guys, but they are usually a small handful of a select few that are often taken high in drafts and quickly make the NHL. A few late-bloomers eventually can make the NHL as well, but I think the KHL probably has more than all of those leagues combined.
It is more common to see non-elite prospects come from the KHL and immediately crack an NHL lineup vs. the SHL (although it is more common recently, usually Russians didn't even bother coming over until they were able to do so). I think unless you are in the top-tier of SHL talent (i.e. top 5 or maybe top 10 talents), you usually need to spend time in the AHL before making it to the NHL... And I think even the likes of Hardy Haman Aktell (a guy who should be among the most attractive Euro UFA's this year, if not the undisputed #1) will likely need at least one year in the AHL before he can seriously challenge for an NHL job. Whereas Grigori Dronov, who is the same age and is also a LHD who should attract NA interest again this year, could realistically challenge for an NHL job next year...
Or we can just look at how Kuzmenko, Bobrovsky, Panarin, Zub, Zaitsev, Mikheyev, etc. all made the direct jump to the NHL after being signed out of the KHL as UFA's and stayed there. I don't think any SHL players have directly made the NHL after being signed as UFA's. Bjork on CBJ is probably the closest to it that I can recall, and that took a crap ton of injuries.
Personally, the more interesting question is where the AHL ranks on the list. I think some of the Euro leagues have more high end talent, but I think an average AHL squad would beat an average squad in any of the Euro leagues. Would actually be interesting to see a modified version of the Champions League involving the AHL if it were not for the cost aspect.
