3.5 All the way. I hated 2e with all its 1001 individual tables to look up utterly every aspect of everything. I dislike the racial caps on advancement in 2e and the racial restrictions on classes. I think 3e did a huge favor by nerfing quite a few things to make them more equitable and also still allow for great diversity and advancement.
Proxies are allowed in Sigil. They represent their respective gods afterall, whom are barred from entering. Proxies aren't godly. Proxies are the souls of the dead that have entered their respective planes of alignment and sworn to serve their Power. Think of them as Executive Secretaries.