1) Loudmax: It makes the track sound weak even if there's no gain reduction at all, maybe it's because of some sort of LPF inside or slow release. Also, it has noise/color underneath so it does color the sound (a little bit).
2) Unlimited: This one sounds awesome and the two sliders to control the transients and color make it very versatile. But there's one big problem with it:
It's unlinked! This means that each channel in Stereo/Surround is processed appart from the others, so limiting anything that isn't mono will mess up the width greatly and introduce weird modulation artifacts.
3) Limiter No. 6: Tons of stuff means many posibilities but also more time to learn, not a problem to me tbh. But again, this one has two problems:
a) It heavily colors the sound: It seems like Vlad tried to make it this way just to make for Molot being a heavily colored compressor too. It even colors the sound when there's no gain reduction being made, the more you process the signal the more mud you get.
b) Its antialiasing dulls the signal, something awful and never seen in any other plugin with oversampling (that I know).
My proposals for free limiters would be:
1) Kilohearts Limiter, it's like the Waves L1 because you do have to set the release manually, but it has a lookahead just like Loudmax (and Limiter No. 6 in some settings):
https://kilohearts.com/products/limiter
I haven't tested ReaComp as a limiter enough, and with the change the to knee maybe it'll sound better to me this time.
2) TDR NOVA 2 followed by a clipper: The new version of TDR NOVA came out late last year and one of its new features (in the free version) was inf:1 ratio. So you can use this plugin like a "manual-limiter" with awesome oversampling and color or no color at all depending on what you choose (Precise and Precise+). It needs a clipper afterwards because NOVA's compressor is actually an RMS compressor with a very small RMS time, so very short-lasting peaks still go through.