Ward: I ask the readers to take into consideration that this post was written based on my experiences and represents my opinions on the game. If you have a different one and disagree with me, do so in a polite and constructive manner, please. Explaining your opinion is a great first step towards a dialogue. :) phasmaphobic:
Fantastic stuff! Thanks for taking the time to write that out =)
My take is a little different and of course mostly rooted in my personal preferences (such as my hatred of 'furries' and thus refusal to include Rawulf or kittens).
Slot 1: My tank which is usually a Dracon Samurai because of breath weapon (can help in early game or clearing out hordes of small critters), speed and critical hits.
Slot 2: Usually I have Vi Domina (human Valkyrie recruitable in Arnika)) after I get to Arnika and rescue her. Her extended halberd reach remains useful for killing distant enemies (IMO even more so than sticking her in a back row) and she makes a decent back-up healer/buffer . There are options to replace her with the Android Monk (RFS-81) or a T'rang Samurai or several other RPCs later but I seldom do so. Sometimes I replace with my Fairy (converted from Mage to Ninja and using Cane of Corpus).
Slot 3: Miles (human thief recruited in Arnika) just because you get him early and by the time you find a better replacement you will have invested a lot into developing him. Sometimes I replace with my Fairy (whom I convert from Mage to Ninja), taking advantage of ranged criticals.
Slot 4: Mook Gadgeteer - The race does not really matter too much as a dwarf or gnome can do just as well but IIRC it helps at some point to have a mook in the party. Gadgeteer because of the Omnigun and the many useful gadgets you can construct in game. Can recruit a Trinnie Gadgeteer in Trynton if you do not create one.
Slot 5: Female Elf Bard - Must be female elf because of useful item to be found later. Bard because free sleep spells and the TON of very cool, very useful instruments you will find. If you do not create a bard then you can recruit an Umpani Bard in the Umpani city/base.
Slot 6: Either an Alchemist or a Bishop of either Elf, Gnome or Fairy race. Alchemists make random potions while camping which can be used or sold for money.
Slot 7: Gnome or Dwarf Priest for Divine magic/healing.
Slot 8: Fairy Mage (will later change to Ninja).
I do not bother with Rangers because, while their detection/scouting ability is nice, it is hardly a necessity and they are at best mediocre back-up healers and as far as ranged fighting goes gadgeteers far outclass them.
There is nothing wrong with Lords as far as stats and abilities go but I just have a personal issue with the gender specific class name (why not call them "Paladins" or "Crusaders" or some such?!) so I don't use them.
Monks I do not tend to use because I personally would rather have a well armed and armored tank dual-wielding a couple great swords than to have the unarmed Shao Lin knock-off.. On rare occasions I will recruit RFS-81 (the android) though.
As mentioned I avoid 'furries' so the Puppy and Kitten races are unused by me.
Other than that I pretty much stick to the tips others have provided here.