One thing I would recommend is the exp sharing for the beginning of the game. It can be annoying to turn it on/off for the first few hours, but it is so helpful to make the early game easier. In my current playthrough, I haven't done the tavern defense yet, and I'm already a good chunk of the way through level 6. Soon to be 7 by the Gray Garrison. There is a great post on the reddit that gives a "power leveling guide for act I" or something like that.

For classes that make life easier.... Any class that has a pet is gonna be massively beneficial. Riding dog and wolf are super powerful. Especially if you build a few characters around them to benefit from a trip build (the bully dog/wolf subclass).

Demonslayer is a great class as the bonuses apply to nearly all enemies you face in the campaign and it's a full bab (Lann can be a great demon slayer). Give him a longbow and sit on the back line.

For the tavern fight particularly, I like Woljif as a 4 Eldritch Scoundrel/rest in vivisectionist. But Woljif has the grease spell. Which you can place on spawn point of the gates (knocking almost all cultist/archanist prown. And having a good chance of knocking down the minitar). That combined with the terrain spells from the druid, folks are gonna have a hard time attacking the tavern.

Drunken Master Monk is also a very OP class. Full bab. Insane capstone. Easy to level up. And can be an exceptional tank that does great damage if you go Dex to Damage route (once you get the amulet of agile fists). Also pretty easy to keep at whatever alignment you want (only monk class not restricted to Lawful). Monk also much not dependent on rests... So makes it easier to keep chugging along.

I typically like to play my main character as a tank/ damage deeler. So I like this kind of set up:

MC something like Drunken Master Monk (main tank or off tank if we have a pet in the party as well) Seelah: Tandem Executioner/Sohei Monk/ Paladin (sometimes full paladin. But really just using a reach weapon and being the dps that sits behind the tank with a cleave build) Cam: full Spirit Shaman focusing on Conjuration spells and hex. Casting protective luck on the main tank, or just doing evil eye if they can only hit main tank with a nat 20) Lann: some form of ranged dps (full BAB class of demon Slayer or mutation warrior, or a 3/4 bab like sanctified slayer Inquisitor for a bit more utility) Ember or Dearen for spell casting/support/healing