16-Bit land has a LOT of really good music, but my favorites are usually a pick-and-mix from random games. However, it does contain one of my all time favorite soundtracks by percentage...
Sonic 2... I love about 95% of the whole track, and was remains is at least a strong like. Get that Sonic 3 out of here, it has nothing on Sonic 2 (but it's still really good). They made alternate versions of the music for the 2-players stages for no damn reason and they where still all exceptional and some maybe better then their single player versions! The weakest songs for me are the special stage which is more utilitarian, and Oil Ocean which is my least favorite stage theme but it's grown on me over the years. Overall I like the SNES' soundfont more, but that Genesis grunge is just so well utilized in Sonic 2.
Donkey Kong Country 2 probably comes in second by percentage. Maybe 80% falls in love territory, but it reaches higher highs then Sonic 2 for indivual tracks. Bramble Scramble is among to most legendary video game tracks ever, and recently it seems Mining Melancholy is getting the love it has deserved for years. There are no tracks I hate, but some are a little more average to me.
Those 2 are always going to be popular choices, but I have one I don't think a lot of people would say - Kirby's Dreamland 3. Kirby 3 has the most Kirby soundtrack ever. It's just that right balance of relaxing, lazy and frantic. It's a really special soundtrack, I can think of no OST that has more warm, happiness inducing songs. No other OST brings back the same memories of my youth and gives me such a bittersweet feeling. I am seriously unable to listen to Ripple Field 1 without tearing up, I have no idea why.
Final Fantasy, Chrono Trigger, Mario, other DKC and Sonic games have a lot of great highs, but by percentage of the OST these ones stand above for me. At least in the 16-bit era.
P. S. Michiru Yamane worked on some excellent music for Rocket Knight Adventure, which is a 16-bit game I am mentioning just so I can say that Symphony of the Night who's music she also did is the best OST in all of reality.
