Mustangs,
You will open a BIG can of worms with that question?
There are very strong opinions on all sides about all sorts of wood finishes, oils and varnishes. A lot will depend on what look YOU like and the time and effort you are willing to put in yourself or dollars to pay someone else to do it for you. There are also many resources, techniques and tips available to help the DIYer.
My personal experience; I tried Interlux Schooner varnish on the stern cap rail and teak dorade boxes covers. I took all the previous stuff off down to bare wood and followed the instructions to the letter and applied 7 coats in controlled indoor conditions. After 2 years it started to fail.
My toe rails were in very bad shape (over 8 years of no nothing) and I needed something to at least stabilize and protect them from further damage. After much thought and discussion with others I scraped and sanded to bare wood, then applied 3 coats of Sikkens Cetol Marine Light followed by 2 coats of Sikkens Cetol Marine Gloss. No sanding between coats! I have no regrets and most anyone (except those with a professional eye and experience) probably will not be able to tell the difference between varnish and Cetol light with gloss over it from 30ft+.
There is a new Sikkens product available this year: Cetol Marine Natural Teak, but I have not seen or tried it.
For varnish, I am using Epifanes wood finish gloss and Epifanes Wood Finish Matte. Again it is easy to use, builds fast and most important - no sanding between coats!