ATHENA, COMETIC, WISECO, or K&S KITS.

are they are all made of same materials?

who's the bestest? cheapest worth it?

gasket-goo? will that blu loctite gasket stuff do?

Personally I only ever buy original equipment or higher spec. If you know where the manufaturer (YAMAHA) gets their gaskets from, then it's cheaper to go direct. I'm sure someone knows, but I don't, sorry.

I had my engine rebuilt using genuine YAMAHA parts, because I didn't want it to go wrong and didn't have time to shop around a lot.

I only had it built for me, because I was busy building the bike

I usually use a little Hylomar Blue on gasket surfaces and I always use new gaskets, BUT BE CAREFUL!!

You musn't get the blue past the inside edge as these bits will wash of and potentialy block oilways!

A drop of oil wiped neatly on surfaces that meet with rubber gaskets.

Rebuilding an engine is quite straight forward if you have a manual with tolerances, clearances & torque settings and all the tools and measuring equipment.

Never use universal gasket goo, unless you simply cannot find (buy) a gasket for that part on a classic for example... these are for emergeny use only and not really a permanent solution. The best thing to do for that is to get gasket sheet, mark it and cut it very carefully. This takes a lot of time. I used to service Mercs and Rollers and restore classic cars ...