I think I have tried every make of guitar string on the market over the years or so it seems.. but for my 510 I have always gone back to Elixer Nano mediums.. to me they sound the best on this guitar..Incidently when I purchased this guitar new in 96, Taylor were using D'Addarios on most if not all guitars I believe and some time later (not sure when) they moved to Elixers..
But for other guitars, a martin, Blueridge, Walden, I use D'Addario EXP 17s which sound (again to me ) better than Elixers on these guitars.