I have played ToS on both Brower and Steam, and given the number of alleged hacked accounts, there is most likely more issues with people logging in through steam. I mean lets face it Steam's security measures are complete RUBBISH! Its a chore to keep changing your passwords and info on steam, but Oddly enough it does help.
But some things I have noticed that are Pros and Cons. Though truthfully, the LAG is getting worse on both sides. I am not even going to mention the mobile version due to given what you are playing on, be it cell phone, tablet etc. There are way too many variables.
PRO:
Steam: Better quality of gameplay, as far as graphics, smoothness, and over all better UI actions.
Browser: Less Chance for getting hacked, easier to access as far as logging in, achievements properly register more. Does not freeze up when you tab out like you do with steam. Uses less RAM than steam.
CON:
Steam: Higher chance of being hacked, When steam's population gets high it lags very badly due to what ever server they use being crowded, tends to lag out, freeze or Disconnect more. Plus not to mention Steam has been having all kinds of issues as of late. a lot of achievements are not being registered properly.
Browser: graphics are grainy or pixilated, tends to be susceptible to pop ups, and other random things.
These are just a few of things I have noticed. If anyone else experienced similar issues, or has an opinion, Please share it here.
I also wonder, with this new Unity Engine, for those users who do not use steam, or the browser, are you going to make it available to be played both through steam and/or Browser?