I ended up getting the Masterlock cuffs as my lock, because I thought it would be more versatile than a u-lock and because it is rather difficult to pick. I'm not sure that a u-lock wouldn't be easier to lock up to railings and such, but it also has a guarantee wherein Masterlock will reimburse you (up to $3k) the cost of your bike if it is stolen (conditions apply). I figure it will cover the $1K deductible of my homeowner's insurance and my homeowner's insurance will cover the rest. Hopefully I'll never have to make a claim, because I really love my bike.
However, the
motion detector alarm that I put under the seat gives me the most peace of mind. Only $15 on Amazon, it works well, and if anyone jiggles the bike in any way to mess with the lock or any part of the bike, it makes a hellacious noise. Quite effective!