I guess I'll weigh-in here on the mods thing. While I have the Ninja 300, I also am a fan of the R3 and just got to test it. With my Ninja, I really wanted to see what a lightweight sportbike could be with respect to mods, but I think mods for these tiny bikes are kinda all-in or not. I went the full-bore route, in-part to show all of this on YouTube and also to see if I could make a fun sportbike that much more fun. So, I have the full-exhaust, custom tune, quickshifter, shorty levers, Woodcraft clip-ons (The N300 really needed them), EBC HH brake pads, double bubble windscreen and a bunch of other mods. I also have Pirelli Diablo Rosso II tires, 15/43 gearing, new chain, tail tidy, chassis protection, TechSpec tank grips, seat cowl, etc.
The bike is simply a dream in the canyons. I mean, these little bikes can be made so good (and with a boost in power) where you may not want anything 'bigger' or any kind of upgrade. On the freeway I think they're still lacking compared to the supersports. So, you not only make the bike lighter with these mods, but faster too. It really starts to transform how it feels to ride it. Just changing the rear tire from the stock IRC to a Pirelli Diablo Rosso II shaved-off 3.1 lbs. of unsprung mass, which is the best kind of weight you can remove. That weight removal by itself improves braking and acceleration for the same reason that lighter wheels improve it, not to mention better warm-up time and better outright grip.
What I've been doing is letting people try my nicely modded 300 and it's been getting rave reviews...and even vlogger BakerXDerek gave it a '10'. But, the same treatment can be done to the R3 to really push the envelope and make it so your bike is totally running sweet, at its max reasonable HP and catered to you. It's hard to appreciate those differences until you experience a bike that's been fully-modded.

It's like night and day. In fact, I probably would have sold my Ninja by now if not for the improvement I got from the clip-ons. Those stock bars were way too high for how I ride in the canyons. And, the Pazzo levers made a huge difference from those stock levers with the clutch bite point super far from the grip.
I think the R3 is more refined right out of the box...and some choice mods would have it singing in no time if it's a project you want to tackle.