In my opinion and experience bristlenose plecos are the perfect pleco. They stay small (max 5-6"), they do well in almost any temp and type of water (soft, hard, etc.), they eat almost any type of algae, and they don't bother anything (plants, discus, fancy goldfish, etc.).
Plecos do not need fruits and vegetables necessarily. They do need a complete and balanced diet like any other fish though. This can be through a high quality pellet or through variety (including said fruits and veggies). I would consider driftwood essential to them though. They will eat it, and obviously love to hide in and on it.
The largest common plecos I have seen in person were 30-36" and I have heard reports of them getting larger.