I tried Zebra Sarasa, Pentel Energel, Pilot G-2, Comix, Bic Gelocity, Bic Gelocity Quickdry(indeed they are very different inks), Muji, Sharpie S-Gel, Unibal Signo,... probably even more, but Energel indeed is in a league of its own. I would put Bic Gelocity Quickdry as close second. Which surprised me. Though their pen cases suck(rattling noise while writing, changing writing angle can mitigate this). Also not all tip sizes are equal. Pilot G-2 0.7mm writes like Pentel 0.5mm for example. You have to find the one you like the best and it mostly comes down to your preferred tip size. To me, 0.5mm or 0.35mm will always be scratchy, no matter how smooth the ink is. 1mm can be good but 0.7mm is just the sweet spot for me. Also not all black are equal. I think Zebra wins here. Uniball is the worst(can become almost gray).
YMMV.