Anyone a fan of the Scottish mysteries?

I'm not sure I know any. I would love to hear about some good ones!

Stuart MacBride is probably the most well known, he writes the Logan McRae series. They're police procedurals, gritty and dark with a few horror elements. I find his books hit or miss, when they're good, they're fantastic but they're not always good. Everyone I know seems to like his books more than I do, so maybe it's just me..
Cold Granite Stuart MacBride

A writer in the same vein would be Ed James and his Scott Cullen series. The first book in the series is free on Kindle (if you don't have a Kindle, you can always download the Kindle app to whatever device or computer you have). What I like about his books are the characters, especially the Scottish vernacular in there. Plus his plots are quite good.
Ghost In The Machine Ed James

James Oswald's Tony McLean series mixes a police procedural with elements of the supernatural. This is probably the first Scottish mystery I read and I was hooked. His first book, Natural Causes is also free on Kindle, but also available in bookstores. I highly recommend this series, book 5 just came out in the UK and I wish I had teleporter to go over there and buy it right now.

Ian Rankin is another well-known but I've never read his books. He writes the Rebus series (which I think was adapted for TV?) and I've heard nothing but good things about him. Haven't gotten around to reading him myself, though.

Big fan of the Rankin mysteries here. To the point that their Edinburgh locations have become fixed points of reference to me during visits, as much as the locations related to Scottish history ... ;)

Rankin is an excellent writer, and Edinburgh almost is a character in and of itself in his books (though clearly, the books wouldn't be the same without Rebus and his partner, Siobhan Clarke). If you ever get around to reading them, I'd recommend to read them in order, however -- both Rankin's writing and Rebus's character has evolved significantly over the course of the series, and later mysteries often allude to the events of the earlier books.

Another good Scottish writer, whose books are set in Glasgow (and typically have female protagonists), is Denise Mina. She has written the "Garnethill" trilogy (named for a Glasgow neighborhood; the protagonist is a young woman named Maureen O'Donnell), and the Paddy Meehan series, named for its protagonist, a journalist named Patricia ("Paddy") Meehan.

I love books with atmosphere and it sounds like the Rankin books have that. So many books, so little time! How does one decide what to read next?!

Hehe. The quintessential bookish problem!