Unsurprisingly, "optimum" parties in MM7 are very different for Light and Dark, and I'm sure you remember that about half-way through the game you will be required to make an irrevocable choice between the two. So first thing to say is that your starting party should be chosen with your eventual choice in mind.

Regardless, I believe your first character choice in MM7, at least as a non-experienced player, must be a Cleric. Cleric gives you a bunch of useful Body Magic protections & buffs that are even more useful at GM level, but the most crucial of all of these is GM Protection From Magic. This gives you immunity from eradication, instant death and all those annoying one-shot-kill attacks that can mess up an otherwise standard fight.

Secondarily, a Sorcerer could also almost be considered a "necessary" character for a non-experienced player. You need at least one player able to GM Water Magic: firstly, Town Portal for fail-free escape from situations that don't turn out as you want. And secondly, Lloyd's Beacon obviously makes travel much easier. LB is a GM Water Magic spell in MM7: unlike MM6, all spells in a school aren't able to be learned by anyone who has the magic skill. Spells in MM7 are only able to be learned if you have the necessary level in the skill.

So I'd be starting from a point of having a Cleric and a Sorceror, regardless of might/magic or Light/Dark preference. The other two characters will definitely depend on a number of factors.

It's commonly accepted that might parties better suit the Light path, while the Dark skills better suit magic parties. Given your comments, I think your first choice should be whether might/magic or Light/Dark is your primary preference.

If you choose Dark, then Shrapmetal will generally be your primary combat strategy (eventually). I note from other posts that you haven't really used it before and don't necessarily see the value, but I assure you it's the single best combat spell in the game at GM level. Because of the way that the fragments fly out in different directions from the caster, Shrapmetal is all about getting right up close & personal with the opponent (generally melee range, and perfectly as close as possible), centering the opponent on the caster (remembering the "position" of the various characters from left to right), and letting fly. With a Dark party you will relatively quickly get to a point where Shrapmetal outclasses any melee damage, so the consensus ultimate Dark party seems to be CSSS, which gives you healing and GM Self magics (including PFM), and allows all characters to cast GM Shrapmetal. But is a little one-dimensional, and vulnerable at lower levels. People seem to like it to allow specialisation of their Sorcerers and maximum waypoints with Lloyd's Beacon, which allows them to pump Dark Magic (ie Shrapmetal) without having to spend skill points to max out all four Elemental schools.

For alternatives, with Dark Magic there's no point substituting a Sorceror for an Archer, which gives you no Lloyd's Beacon and no Dark Magic in exchange for average melee. But a Druid is a solid choice, especially as a character that may traditionally get ignored. A Druid gives you the same Elemental magic as an Archer but also a second healer. Similarly, a Knight may help you in the early stages but quickly gets outgunned by Shrapmetal, whereas a Thief gives you solid muscle & melee in the early stages before you develop Shrapmetal, but also Disarm. So in all, I'd start with CSSS and depending on preference, swap one or two of the Sorcerors for a Druid and/or a Thief.

If you choose Light, you're absolutely committing to melee as your primary combat style. I've used KKCS with great success if power-gaming is your thing (or KTCS if you want traps to be easier), but again it's a little one-dimensional. A popular alternative, especially if you prefer a blend of might & magic in your party & fighting style, is PACS. This gives you double healing & double Town Portal (albeit only at Master level for the Archer), but every character also has access to Light Magic. This is definitely overkill for the vast majority of the Light spells (once you get up the standard GM protections and buffs, they last for days), but you do this for one specific reason: it allows every character to cast Paralyze, which is the most useful combat-based Light spell in the game. It can sometimes end up with 4 characters unsuccessfully trying to Paralyze a single opponent over multiple rounds while 10 others beat down on you, but against a smaller number of opponents, when it works, it makes combat a breeze.

The final thing to mention (because I'm sure Peter2 will say this anyway!), is that the Light-path-specific quests are arguably more "satisfying" than the Dark path quests. The Light promotion quest in Light territory gives you some interesting non-combat options, and a Light party getting into Dark territory is definitely a tougher battle than a Dark party moving around in Light territory (although it's entirely possible to run around avoiding combat until you're strong enough to wipe out the enemy easily, rather than fighting to clear the area as soon as you are able to enter, which is Peter2's much-loved strategy of "Light party taking on The Pit).

Hope that helps