Well these are just my opinions and clearly people are free to agree or disagree as they wish...
1. I liked Deadpool 2 better, simply because I highly anticipated it versus the "meh" feeling I had prior to Solo. I also liked DP2 better because whatever craziness you saw on-screen, you could just say, "Well that's Deadpool." Whereas with Han, that character was played by newcomer playing a legendary Hollywood icon; and fans of Star Wars have extremely specific ideas of how Han should be played. It was a tight-rope that I thought both Ron Howard and Alden Ehrenriech walked pretty well.
2. If someone has a preference for crude humor and comic books, Deadpool. If said preference is for science fiction fantasy, Solo.
3. I really have no opinion on which film was cooler because they're such different genres. The only thing they both have in common is that they're fictional. I guess if I was pressed to answer though, Deadpool was cooler simply because they had more latitude on profanity, inappropriate jokes, and overall crude humor. Not sure what that says about me though.
5. Honestly...this is a tie. I loved how Solo, at the end, tied into the beginning of the Rebellion. I thought Donald Glover gave a 100% believable performance as a young Lando. The new young guy who plays Chewie is nearly seemless with Peter Mayhew's take. Emilia Clarke was perfectly cast as Qi'ra and I appreciated her seemingly two different takes on the character. Surprisingly, Woody Harrelson was better than expected and I loved that Han shot first.
Deadpool though, was equally good. Zazie Beetz made the perfect Domino. Thanos, I mean Josh Brolin, brought Cable to life in a pretty authentic way. Brad Pitt's cameo was hilarious. The jokes, "Hey...slow down on the hate Fox and Friends" references, and the overall messages of the film: family is important and preventing kids/people from being abused today, can spare pain and suffering in the future were all blended incredibly well together.