3 fish questions: gold tetra, dwarf pencilfish, & Oties

Oto's are not known for jumping. They need lots of cover, but a planted tank is usually adequate for that. They don't do well in tanks that are new or unplanted.

Pencil fish tend to be fairly well behaved in community tanks--they are not aggressive towards other fish.

I'd go with the pencilfish--depending on what fish you mean by 'gold tetra'. There are gold neons sold sometimes that have a parasitic infection that modifies the normal colors of a neon tetra to look gold--I'm not a fan of them, and they are more delicate than even normal tetras.

If you are asking about the gold tetra Hemigrammus rodwayi, they are very sensitive fish. I can't personally compare them to dwarf pencils, but I would think (from what I've read) that the pencils would be a bit easier to keep. In hard water with a ph of 7.6, 6 out of 8 of my gold tetras died. In water with a ph of 7.0 and a bit softer, 13 out of 13 are going strong. They don't seem to do well in alkaline water.