Pathfinder 1e General Discussion

I figured the 5-foot step would have come up in your one-shots, so I didn't bother. But yeah, it's an important tactical option to be aware of, both when considering your own options and when considering your opponents' options.

There are a couple of magus-specific pieces of advice I can give.

Spell Combat and Utility Spells

First is that, in terms of action-economy, your core class feature is not spellstrike, but spell combat. Spellstrike helps you deal more damage and feel like a bad-ass, but spell combat lets you do something pretty unique: Cast your buffs and debuffs while simultaneously dealing significant amounts of damage. It also acts as pseudo-two-weapon-fighting if you cast a touch-range cantrip (such as arcane mark) just so you can deliver it with a spellstrike.

In summary, it's better to think of yourself as a bad wizard who can also deal a lot of damage, rather than as a martial that deals damage by casting spells.

The Specifics of Spellstrike

Second, the way spellstrike in particular works interacts with some rules that don't come up very often and have some details that are easy to miss. I'm talking about the way that delivering touch spells work, and therefore by extension the way that delivering a spellstrike works. When you cast a touch-range spell that affects a single target (such as shocking grasp), you don't actually deliver the attack as a part of casting the spell. Instead, casting the spell grants you a free action that you can use any time in the same turn to deliver the spell. This means that you can cast shocking grasp from a safe position, move, and then deliver the shock (as a spellstrike in your case) as a free action. Of course, if you're using spell combat, you can't also take a move action, but you can still begin spell combat from five feet away, five-foot-step, and then attack.

However, if you miss, or otherwise don't successfully deliver the spell on that turn, further attempts to deliver it on later turns are their own attacks, made however you normally make those attacks; e.g. as a regular attack action or part of a full attack, or even an attack of opportunity.

How this interacts with spell combat is that you can cast the touch spell as your spell for spell combat, take your free action to deliver it immediately, and then even if you miss, the rest of the attacks in your full attack can each attempt to deliver it.

Magic Item Crafting

Magus being a spellcaster, and an intelligence-based spellcaster at that, means that you are indeed one of your party's first picks for magic item crafting. A wizard, with their bonus crafting or metamagic feats, would top that; you're going to be a little more starved for feats than the wizard would be. But lacking one of those, you're the first choice. That being said, you don't have to take magic item crafting feats if you don't want to bother with that—or if your GM doesn't want to bother with that—as long as decently-sized settlements where you can stock up are going to be available. Like I said, it depends on the campaign.

While I appreciate how much customisation there is—and that it meaningfully impacts your style of play, rather than just changing out some small bonuses—I also appreciate that you can always decide that you're just done, pick no archetype and some bog-standard feats from the core rulebook, and it's good enough, though not optimal.

Oh for sure, my current class obsession, the medium, requires reading up on the entire wizard, cleric, druid spell list in addition to your own, as well as prepping contingencies for weapon combat, temporary skill & occult unlocks, and figuring how to even use two more chasses that don't touch any of those options, all before you start getting into the advanced cross-spirit synergies, like necromancy and body possession, let alone the customization options you mentioned.

Of course, then there are also your barbarians who really only need to know to hold their sword two-handed & be mad, so it's not all chargen insanity.