Robert Jordan's passing made me think of this genre and how much I used to like it. My interest has somewhat faded but there are definitely a couple of very nice reads out there.
My personal favorite is Guy Gavriel Kay
http://en.wikipedia.org/wiki/Guy_Gavriel_Kay
His books are not one series as such but they are all set in an alternate medival universe that much resembles our own history. I have probably enjoyed
Tigana the most, with
A song for Arbonne and
Lions of Al'Rassan as runners up.
I also really like Katherine Kerr's
Deverry Saga up until around book 6 when I started losing interest.
Please point me in the direction of other worthwile reads.