The only contests I have worked so far have been Field Day, on and off for the past 20 years. I always run 6m for a local club and only log with paper. I can write and log faster than I can log on a computer so I have only ever used paper during the event. Post event, I simply use a text editor and "import" my log into the Cabrillo format and send it to the club for inclusion into the aggrigate Field Day submission. *IF* I were to purchase a logging program, which I may soon do, I'm looking really hard at N3FJP's software suite.
The only problem I have seen with POTA and FL-POTA is that they want their logs in ADIFF format, so will need to find a logging package that will do both.
73!