I’m probably doing my 3rd character this week. Once you get one up to 20 it is pretty quick to level up and gear a character. My 2nd one was at gear level 270 in less then 2h after finishing the story. Copying over some weapons to get an initial boost works nicely.
I really recommend getting all classes however. Once you get stuck or bored with another class, you can just jump to a different one and play that instead. I will use different factions for each of them too, as every faction has something I like. You can also adept to what is needed in raids or nightfalls . Unfortunately there is no incentive to have multiple characters of the same class.
Up to now I love my Ranger, the Titan is okish. I find the ultis on the Titan really boring up to now but I like that it is far tougher. Still it didn’t really grew on my till now. The Warlock really annoyed me initially with no double jump, gonna play her next.
BIG tip, some of the weapon rewards you get from certain milestones are really good. The Nightshade and Nameless Midnight for example. You might wanna stick to those and level them up or just keep them in your vault. If you do multiple run-throughs you can choose a different one each time and experiment which you like better. Right now I really enjoy the Nameless over my Mida. The special pump shotgun from Hawthorne is another example, if shotguns are your thing .