If one has to ask what to put on his own gun, then the owner doesn't yet need it.
Magwell.
Try practicing reloads without the magwell first. Glock's existing magwell is already large, being a double stack, and tapered. A magwell doesn't automatically make one faster at reloads.
Grip Products.
Talon does make a good product. There are other brands on the market which are also good. DecalGrip is another brand. If money isn't an issue as you've mentioned, then consider finding a Gen4 to buy via PPT (private party transfer in CA).
Metal Guide Rods.
These generally won't help you. One good thing is if you get an uncaptured version and want to experiment with different spring weights, this is the way to go. Reliability can suffer with different spring weights and one will need to thoroughly test one's equipment to determine specifically which ammo runs with what spring weight; then also how long that spring & ammo combo works prior to failures developing, such as, failures to return to battery; or short stroking.
Metal Pins.
Two of the three pins in your Glock are already metal. They just don't have the white metal bling-look. I've also seen aftermarket pins break, specifically the locking block pin which seems to take the most beating. NEVER use a hammer or mallet with these pins. If you do, you're doing it wrong.
Trigger.
Yes, it has one and it works well. Experience with Glock's trigger is important in that if it's different from other Glocks, an experienced person can feel that and perhaps know what needs to be done. Conversely, an experienced person can also tell the trigger is fine. There are all sorts of companies selling trigger kits costing hundreds of dollars. Perhaps these kits are required for the folks who actually win in competition. If you need that trigger just to place or compete, then stay with stock as you primarily want confidence & reliability which a stock Glock trigger provides. Picture spending $200 on a trigger kit; going out onto the line in a competition and having your one & only Glock trigger fail to reset or worse, multi-round burst.
Sights.
If you can't tell if you like or don't like the stock sights, you don't need new sights. Every combination of sights sold are marketed to be the best thing for you. Buy the sight installation/removal tools; then every week, shoot 1,000 rounds with a different set of sights; then come back here and tell us which sights are best for you. You may want a chronograph, too.
Picture this scenario. You go out with a completely stock G17gen3 and you totally win your competition with it. There's a GSSF match this weekend, by the way.
Many of the aftermarket parts are good, but they have to work well with you. They may not benefit someone else. Some parts may be a hindrance for you, but not for others.
The Math: 50 sets @ $100/set. $5000.
1000 rounds of ammo at 50 weeks at $300/1000. $15000.
Mag Catch.
You don't have to justify your need of a larger mag catch because you've got small hands. If it works for you, then install and use it. You may want to buy an extra mag catch spring as there are some videos which can have someone more easily permanently bend the spring which can make a mag catch unreliable.
Try to minimize bending and pull the entire spring out with needle-nose pliers. The old-school method of "armoring" has one leave the spring in and bend the spring out of the way as much as necessary. This older method can more easily put a permanent bend in the spring. There will need to be some bending just to get the spring out of the old notch and into the new catch's notch, however.
The larger mag catch can have it's drawbacks; inadvertent mag releases are what comes to mind. One has to ensure the mag catch works well with that person and that person's holster setup. I went with a standard length mag catch on a G35gen3 instead of the supplied extended version due to this.
I'm just kidding.