The new Penguin Classics edition (published 2015), translated by Nigel Cliff, is good. It's the first major translation in the last fifty years. The translation is good, and easy to read. It's based on a good manuscript ("F", from the French National Library), and uses other manuscripts where they have sections missing from F (and the use of these other manuscripts is indicated).

Apart from being a good modern translation, it also takes advantage of modern scholarship, such as better identification of the places that Polo names.

A review of this translation: Haw, Stephen G."The Travels by Marco Polo (review)." China Review International, vol. 21 no. 1, 2014, pp. 23-27. Project MUSE, doi:10.1353/cri.2016.0058 https://muse.jhu.edu/article/627677/summary