This question has been discussed on other forums as well.
KPRepublic is cheaper, and a fine value option.
But KPRepublic sets are known to have really serious legend issues. I might be able to dig up a picture later, if necessary.
A few days ago, I saw a photo of someone's custom using KP 9009, and the bottom row was a mess. Just a disaster. The text had been stretched vertically, as if it were melting. Like if you took text that had been created in MS Paint, and then stretched that text vertically with the resizing tool.
There are also some comments about keycap consistency. But most of the complaints are about legends.
One thing that's hard to come across on-line is the feel of the material. ePBT uses Gateron blanks, which are generally highly-regarded. The feel of the keycap surface is very good. They are premium materials.
For me, it's about the switches. ePBT 9009 feels 'heavy' on light tactiles like Browns, and not ideal. But on Zealios 62 gr, for example, the tactility is brought out very nicely by those same keycaps. After trying ePBT 9009 and Zealios (R11) on my switch testing keyboard, I know I want a board with similar components.
Definitely read this review of ePBT 9009:
https://brianlee.blog/2018/07/26/review-enjoypbt-9009/R2 of 9009 still had issues with legends, though not as bad as R1. The real problem with ePBT is that I'm not sure it's ready-to-go out-of-the-box. As Brian Lee mentions in his review, there are still issues with 'flare,' or extra bits of plastic protruding from the bottom of the keycaps. They weren't shaved off or removed during the manufacturing process, so you need to do it yourself. It suggests that ePBT are a 'hobbyists' keycap that need work from the end-user.
And there continue to be issues with warping of the large modifiers, such as the spacebar.
Neither KPRepublic or ePBT 9009 are perfect. But ePBT has arguably better materials, and by R4, probably better legend quality.
Here's my Filco Majestouch outfitted with ePBT 9009 r4:
https://imgur.com/a/7ZFbQrY
