You can have splendid rides in all islands. Fuerteventura is more hilly than mountaineous. Gran Canaria has a little bit of everything. Tenerife is hard all the way.
The Teide (up to the cablecar) is absolutely recommended. I climbed it 3 times in 1 week. It killed me.
I did twice from Granadilla/Villaflor. This side has splendid asphalt and a lot of curves, but all with a good overview of what will come. You inevitably descend faster than cars. This was the highlight for me (together with Masca).
I did the Teide once from the guia de Isora side. This side has bad asphalt with many potholes. Not recommended for descending. http://goo.gl/maps/0MdjV
I have not done the Orotava side, but this must be very scenic, too. The TF-24 looks like it is following a ridge, so this should be excellent for the views.
Most rolling roads are quite busy with traffic. The roads up the Teide are usually very quiet in the early morning, and you will probably have less wind going up. Not so later in the day, when a lot of tourists with rental cars go up. But in general, it never feels overcrowded. The Teide is a unique mountain. It has one of the best calderas I have ever seen (and I have been to Mount Bromo). The TF-21 through the bottom of the caldera must be one of the best roads in Europe. http://goo.gl/maps/AmtVi