Another vote for buying the nicest you can afford, with two caveats:

  • make sure in the "afford" equation you include at least some gear to get you riding safely and comfortably right away (do you have a newer helmet? padded shorts? gloves?) and

  • most importantly, take some time with a few bikes and really get a sense of how road bikes fit, and how you fit on different road bikes.

A higher end bike that doesn't fit is worse than a 15-year old mountain bike that does! (speaking as someone who rides an 18 y.o. mtb with slicks as my daily commuter, as well as a FANTASTIC custom road bike that took a while to save for!) Good luck!