Publish few papers on good or many papers in worse conferences - reputation-wise?
I'll suggest that trying to game this out in advance is a mistake. You will miss opportunities and focus on the wrong thing. Do the research. Write the papers and only then decide on an appropriate venue. If you think that a bit of extra effort on a certain paper might help it be accepted in a better conference, then do that. But otherwise send it to an appropriate conference. If you wait a year, trying to improve it, you will get scooped in a hot field. 

You don't want to be the person that only ever did one significant thing and was otherwise unknown in academia. 

First the research, then the papers, then decisions. That is different from not  having a goal, of course. 

But being present in lots of conferences also lets you build your circle of collaborators.