Not sure if it my favourite, but certainly memorable;
Going north on M77 and wanting the M8 to head towards Loch Lomond, and relying on satnav. Loads of lanes and junctions, you join the M8 going the wrong way and then Google Maps directs you down a slip road to a roundabout so you can turn around and head back the correct way.
Except that halfway down the slip, you notice that you are being directed to apparently turn right onto the roundabout, and suddenly you have taken a shortcut under the motorway through a wiggly width restriction in a contraflow alongside the roundabout, and then pop out the other side
Its a mess of a junction and terrible for commercial vehicles (who are cutting across two lanes of traffic all sitting in that blindspot where cyclist get killed) to get off at the slip road with the chicane) – and thats the improved version. Basically when they built the intersection between the M77 and M8 they didn’t include any facility for traffic reaching the end of the M77 to turn west or for east bound M8 traffic to join the M77. Prior to the the wiggly chicane thing under the flyover the motorway traffic in both directions had to leave the respective motorways a junction early and cut through Bellahouston, sending a 100,000 cars a day past the front gate of a primary school.