After experimenting with multiple connectors, springs, tigger bars, and shoes I'll give you a quick breakdown.
First, do the $.99 cent trigger job (I used a dremel with a cotton head), a bit of Flitz and polish the connector, trigger bar where it touches the connector, safety plunger, and any area's where parts rub. This will reduce the trigger pull slightly (<.5 lb) but also make everything much more smooth in the pull.
I would start here, but if you want to tinker, here's what I found.
With Glock triggers, it's all about trade offs.
If you want a really light pull you can go with a 3.5 lb/ "-" connector, but the way this is achieved is by changing the slope of the connector. What this does is add a lot more creep to the trigger, so you will reduce the "wall" and have more of a pull through without a clear defined break vs. other connectors.
The next option is the "Dot" connector. This connector was put in the later versions of the Gen 4 Glocks as the Gen 4 trigger bar has a much steeper angle than the Gen 3 and Gen 2 Trigger bar's do. This has a slight angle, about 50% between the "Standard" trigger bar and the 3.5 lb connectors. It gives a nice balance of lighter trigger break with minimal creep, but there still is some creep.
Also, the "Dot" connector with the Gen 3 or prior trigger bars will feel more like a Gen 4 with a 3.5 lb connector as the geometry of the Gen 3 trigger bars is less steep than that of the Gen 4's.
Next, there is the "Standard" connector. This will give a heavier trigger pull, especially on the Gen 4's, but with a much more defined wall and much crisper break.
Finally there's the NY connector, Just avoid this unless you want an insanely stiff pull.
On the Gen 3's it gives a similar feel to the Gen 4's with the dot connector, however on the gen 4's it gives an impressively clean break. The downside to the Gen 4 + Standard trigger bar is your trigger pull is typically approaching 6 LB+.
I personally found latest version of the stock setup with extremely polished internals to be the best option (I have a Gen 4 and currently run it with the Gen 4 trigger bar, Dot connector, and an aftermarket flat faced trigger shoe.)
The final thing you have as an option to adjust the trigger break is the striker spring. You can go with a lighter striker spring to lighten the pull (4.5 or 5 lb striker spring), however note, by changing this you may get light primer strikes on certain types of primers (CCI, winchester).
My favorite trigger combo in my Gen 4 was the Standard connector with the 5lb trigger pull, it was a bit over 5 lb and extremely clean and crisp.
With that said, I changed this out as my Gen 4 Glock 19 is my home defense handgun and I don't want to run a lighter striker spring in it, So I have settled on the dot connector with the stock 5.5 lb striker spring.
I hope that helps, I spent way too much money testing different options and combinations just to find out the guys at glock might know what they are doing.
With that said, A simple high gloss polish with some flitz and a dremmel can do wonders in cleaning up the pull.