I get oddly excited whenever I pair a PDF with an audiobook—there’s something about following the lines on a page while a voice brings them to life. If I had to pick one all-purpose PDF for listening along with 'The Aeneid', it would be a bilingual, facing-text edition like those in the 'Loeb Classical Library'. Having the Latin on one side and an English translation on the other is a huge help when the audiobook either skips a wordy aside or speeds through a passage; you can glance down and see exactly which line you’re on. What I love most is that these editions usually include line numbers and notes, so syncing to an audio timestamp becomes straightforward.
For listeners who prefer a modern, more readable English, I often use a PDF of a contemporary translation in tandem with a performance-style audiobook. Translations by Robert Fagles or Robert Fitzgerald (if you can find an e-book/PDF version you own) read beautifully and match well with cinematic narrations. If you want something closer to the original syntax and scholarly footnotes, a PDF of an academic translation or a critical edition—again, ideally with line numbers—will make it easier to pause, look up a note, and come back in the right place.
Practical tip: whatever PDF you choose, try to get one with line numbers and stable pagination, and make sure the translation matches the audiobook edition if possible. If you can’t buy an edition, I use the Latin text on 'Perseus Digital Library' alongside a modern translation PDF; it takes a little juggling but it’s rewarding. The best companion ultimately depends on whether you want poetry that reads as modern English or a literal, study-friendly text—both have their charms, and I often switch between them depending on mood.