I have successfully used compression joints for a long time. The odd one has leaked after installation, but has been made watertight either by a little extra tightening (I tend to undertighten at first) or a wrapping of PTFE tape.
I have just replaced 2 basins and used 4 flexible chrome connectors, each with a compression joint to connect to the existing pipework. 1 is watertight (Hot low pressure), but 3 (2 high pressure cold, 1 hot)continue to weep slightly, despite extra tightening, a wrapping of PTFE tape. (I even tried a smear of Boss Supergreen PTFE pipe jointing compound - No joy.)
Any suggestions to stop this weeping before I stop crying(and weeping!!) and rip it all out and go back to good old copper pipe, bends and standard compression fittings.