Preface: You can play and finish this game however you want. You paid for the game, so enjoy it how you wish. I don’t like to cheese things. I am not a huge RP person. I could be accused of being a min/maxer.
TLDR: IMO The best party combo is You as Str/Con Trickery Cleric, Lae’zel as a battle master, Wyll, Gale. Pick Shar or Selune for fun options.
IMO Classics are classic for a reason. With only 4 party members, Tank, Healer, and 2 Damage dealers are a good start. Bonuses for ranged, off-tank, and utility.
Starting with the origin characters, you would choose Lae’zel as Tank and Shadowheart as Healer. For damage, you have 3 to choose from. Gale is weak at the start, but probably strongest at level 4. So taking Astarian and Wyll for level 2 fights is fine. At party level 3 and 4 you have your main fights so… Gale has consistent damage from magic missile, utility from other spells, and mage armor + mirror image is good for keeping him alive. Wyll has consistent damage that can be useful for the knockback (though bugged so no fall damage), utility, and Mirror image for defense. Astarian has good damage, but it is inconsistent (due to bugs?), no unique utility (other classes can sneak, open locks, disarm traps), and is very squishy. Also the lack of good light weapons to dual wield hurts too. So that leaves us with Lae’zel, Shadowheart, Wyll and Gale.
Now, what character should we play? We can min/max a better character than any of the origins, but is it significantly better? For Lae’zel, Wyll, and Gale – I don’t see it. Shadowheart on the other hand can be improved quite a bit.
Some people think Trickery is a dumb choice. While I like the advantages of Life and especially Light, I can’t get past the loss of Mirror Image. It increases your survivability so much. So, I stick with Trickery. However, I like a Gold Dwarf with 14 STR, 12 DEX, 16 CON, 8 INT, 16 WIS, and 8 CHR. Same STR for damage, but better weapon options from dwarf. 3 higher DEX gives you +2 AC. 4 higher CON gives you way more HP (most in party) for a huge survivability boost and your spells requiring concentration are much less likely to break on damage. What are the downsides? 1) Immunity to sleep as Half Elf is better than Immunity to poison. 2) 4 lower CHR means bad news for dialog choices…use Wyll + Buffs.
What about Cheese Wizard? (Gith Wizard w/ dumped INT using 18 INT Ogre headband wearing Lae’zel’s armor) Search YouTube for examples of soloing the game with it. Totally cool/viable. Obviously Lae’zel is less useful. Also note that at least on the character sheet, your Spell DC sucks. Since you are mostly casting buffs and magic missile, its not a big loss…but be aware. I don’t like to cheese builds or combat; your mileage may vary.
What about Ranger? Love it. If they make it so Colossus Slayer stacks with hunters mark consistently, my opinion might change. I really enjoyed my play-throughs as a DEX Ranger, and especially a STR Ranger (better weapon choices, big damage numbers, great mobility, and utility). But is either build an overall upgrade to your party, especially when you have to go back to Shadowheart as your healer? Not IMO.
This party has good synergy w/ Wyll and Gale up high ranged and you and Lae’zel in melee. You can melee and cast heals at the same time. Two pets including Imp (2nd best pet in game) makes your party even stronger.
Am I saying you have to do this? Hell no. It's your game. Play it how you want. Solo Cheese Wiz, all min stat rogue, etc. can be enjoyable and beat the content. You do you. I really enjoyed playing some non-optimal characters/parties. Dual cleric so you can keep Bane or Fairey Fire and Bless up is pretty powerful. The Ranger Beastmaster Spider companion is awesome. But if you are struggling and don’t mind having a main as a non-charismatic cleric…give this comp a try.
PS: My Combat Tips Guide: https://forums.larian.com/ubbthreads.php?ubb=showflat&Number=722075
EDIT: With now 330 hours played, I just today found out that you could throw food and potions at downed party members. I haven't even tried it yet. I assumed that the only way to get them back up without going to them was a cleric's ranged heal. Soooo that kind of invalidates my above theory and I guess I am going to have to go all Damage Dealers and see how it goes. Good thing I love this game LoL. I do kind of think throwing food at a downed character is cheesing...gray area at the very least. Kind of like Cheese Wiz...but not as much so??? Dunno. YMMV.
Also the above party is still strong, just maybe not optimal if you are willing to literally cheese heal. (Get it? Cheese heal...like throwing Waterdhavian cheese at them is a cheesy mechanic...Sorry I crack myself up.) For example, the above party went to the Underdark today. I hit the Minotaur's from a different direction than normal, so I did not realize it until I entered combat. No planning. No prep. No pre-placement. Still an easy one shot. Same with Duergar fight. No stealth. No cheese. No planning. One shot. Wyll did die near the end of both...guess I should have cheese healed him!!!!