My uncle has been doing contracting work for 4 decades, and he turned me on to Big Stretch a while ago. It’s a great product for caulking around windows and door frames where you expect to see movement as the house moves and shifts around. It’s not designed for standing water or submersion scenarios — for that you want a silicone caulk or the previously reviewed Lexel, but everywhere else I generally turn to Big Stretch. It’s easy to tool with your finger, it adheres really well, and it will stretch rather than tearing. It doesn’t get hard over time, it’s paintable, and it’s a delight to work with.
It comes in a variety of colors, although finding them at a local store can be tricky. The clear goes on milky and turns clear as it cures, which makes it easy to see how good your caulking job is while you’re doing it. It does well reusing a partial tube if you seal the nozzle well (either one of those red caps or some foil tape).
It’s more expensive than other caulks, but if you look at the Amazon reviews you’ll see that the consensus is that it’s worth it. If you have trouble finding it, try finding the retailers in your community that supply contractors.