I like Netscape 3.04, and think it's the most modern tolerable browser on my G3 266. Believe it or not, it gracefully degrades on most sites that aren't Web 2.0, and even works on some forums. Unfortunately, on a 603e 100Mhz, it's like watching paint dry and reminiscent of dial-up, but other browsers are even worse offenders. I prefer to SSH into a Linux box and just run Links. It's at least as compatible as IE 5.x or WamCom 1.3x, and runs blazing fast, too. If I must pick a fast native solution, MacLynx, I guess.
Never had an Internet-connected 68k, but if 3.04 PPC version is slow, I can only imagine how rough the far larger and more bloated 4.0x is. Only for the saintly?