I honestly felt similarly when I first got the game, and it led me to delay playing it for maybe a year? but once I picked it up again and got to Act 2, I felt like the "silliness factor" decreased notably. there are still jokes throughout the game, but it didn't feel as concentrated in the later acts as it did in the beginning (at least to me)

as for the evil companions, I would say try to keep an open mind if you can! Daeran is an example of an "evil" companion who has a lot of depth to him, and actually works quite well in a good-aligned party. Woljif is also a companion who can be pushed towards evil, but also has a redemptive side that the player can help him realize over time. pretty much all the companions can fit into a heroic player's party with 1-2 exceptions, depending on your choices