I use AmiTCP. It's supposed to be hard to set up, but there's a guide floating about detailing the exact procedure. I'll try to find it later! The most obvious benefit is that it's free, and as far I've used it I can't really say that it's missing anything I'd want. I've been using it for FTP and some casual browsing with AWeb on my A1200 + 8mb Fast RAM.
I think that Amikit sells a prepackaged version of this stack that's easy to set up and configure, but with the guide I mentioned, it's really not necessary.
EDIT: The guide:
http://www.acc.umu.se/~patrikax/amiga/guides/AmiTCP_Install/
