I've tried a couple of headers for my 360 and actually want to go back to stock. I have had issues with blown gaskets stemming from the mating surfaces not flat no matter how tight the bolts are. I also hate the rust on the 'ceramic coated' headers. It seems that it is hard to keep them rust free. I have Hedman headers now.
That part about "...and what are people most happy with?", I think you'll find the answer is stock manifolds - regardless if it's an AMC or SBC, etc. I had headers on a 360 - sounded great... when the gaskets were in tact. Similar to Matt's experience, the uneven surfaces, loosening bolts... the gaskets were an issue. And yeah, rust. Unless you drop a chunk of $$$, they're going rust.
I run the heddman fender exit. I took them to my local machine shop and threw them on the belt sander to even up the mounting surface. I also took a cut off wheel and sliced the bridge between 1 and 2, and between 3 and 4 so they could all pull up individual of each other. a good set of gaskets and header bolts and no leaks here. hooked on a set of cheapo glass packs. shot a coat of vht header paint (several very generous coats on the headers) and we were good to go. love the sound.
For what it's worth...I gotta say I have had no problems with my headers. I check the bolts every now and then but that's it. I recently changed out my Hooker Headers (20+ years old) to Dougs Headers and I am very happy with them. The mufflers I have are bit loud but sound nice. With my 304 the Dougs headers have 1 5/8" primaries with 3" collectors and I reduce them down to 2.5" connection to my Flowmasters.