Adventure Island is a knock off of the first WB, yes.
I started with an NES. One day, however, I wanted to get
Super Pitfall for it (which is an atrocious game, btw, and is probably reviewed by the Angry Video Game Nerd or something). My cousin had it, and I had played it and thought it was fun, so I asked for it.
For whatever reason, my mom came back with an SMS. So I had one of those two. A friend of mine who lived across the street had a bunch of games for his, so I played a good number of them. But I had a small library that I kept (and still have the majority of, along with the 3D glasses).
Space Harrier is a good choice, definitely. Ghost House was fun in the "how long can I last" sort of way, even though I remember it getting brutally cheap after a while.
The music of the SMS games is by far some of the best 8bit era stuff you can find. I loved the whole "otherworldly/anime" feel of it all, with those airy, floaty notes and such. It's hard to explain, but the music just had this
quality about it that seems so specifically SMS about it all. Where as a lot of the NES's music is pretty clunky, the SMS had a streamlined feeling. Very ethereal.
There's a good number of games on it I'd like to go back and play and see how they are. I picked up Dragon's Curse on the Wii VC since it's essentially WB

T, and still think it's incredible to think an 8bit machine was pulling it off (I'm aware the version on the VC is actually a TG16 game).
SMS came too late, had no advertising, and didn't have as instantly likeable a mascot. But it was a great little machine and did things the NES couldn't do.