Generally, many traditional VCs do not like convertible notes or safe notes. They prefer traditional priced equity rounds. Fred Wilson, avid blogger and Founder / General Partner at Union Square Ventures in New York have written several blog posts outlining his point of view on the matter.
The general thesis is that kicking the valuation conversation down the line and obsfucating the spectre of dilution to founders and investors alike is not a good idea.
Despite his position, convertible notes and safe notes continue to be very popular. As a founder you will need to do your own research, consult your corporate counsel, and decide what makes sense for you.