Haven't read the Baroque Cycle yet so I can't comment about it but I've heard generally good things.
AH is one of my special favorite genres. Here's a quick overview of some of the stuff in my personal library.
You're quite right to regard Turtledove as hit or miss (and these days he's more miss) but once upon a time he really was the undisputed champion of AH. I'd recommend
A Different Flesh,
Agent of Byzantium,
Worldwar (But not the Colonization series unless you really feel the need),
How Few Remain (but not the multiple series that followed it) and above all
Guns of the South. You might also check out
Ruled Brittania. Avoid the Darkness series if you value your sanity. And avoid the War Between the Provinces series even harder unless you really want a mediocre version of Killer Angels in a fantasy universe.
John Barnes is best known for very thoughtful SF reminiscent of Heinlein but with Timeline Wars he decided to just have fun and
Patton's Spaceship,
Washington's Dirigible and
Caesar's Bicycle deliver. Not traditional AH but you can see it if you squint.
John M. Ford is a personal favorite and
The Dragon Waiting is one of his better known works. Technically it's historical fantasy I suppose, not true AH. But when it's this good, who cares?
Perhaps surprisingly good, William R. Forstchen and Newt Gingrich (Yes, I know, just ignore it) serve up a compelling alternate in
Gettysburg, followed by
Grant Comes East and
Never Call Retreat.
Really the best work in AH is commonly done in short form. I can't begin to list the short story collections but I'll hit what I can recall of the highlights. The various books in the
Alternate ... series (Presidents, Generals, Kennedys are mostly decent as is the
What Might Have Been series.
Well, well, well look what a little research can find.
This is a list of AH collections. don't know how comprehensive it is, but it looks pretty solid.