I think Tiger sals are a little big, especially for someone who's worried about size, I guess I shouldn't have said axolotls either
. Cynops orientalis is the best in my opinion. These animals, are small 3-4 inches, frequently out in the open, and active day and night. The main reasons I say Cynops orientalis are because they are small, and they are more avaliable. If you can handle animals that are around 1 foot long, then both axolotls and tigers are great pets (except for the hiding thing). There are plenty of easy newts in between 4 inches and one foot, they are just not so common in the trade. Some other fairly easy and avaliable, though large, newts are Pachytriton labiatus (±8 inches but terratorial) and Pleurodeles watl (6-12 inches).
So my revised list:
1. Cynops orientalis (chinese firebelly newt)
2. Ambystoma mavortum (tiger salamander)
3. Ambystoma mexicanum (Axolotl)
4. Pleurodeles watl (spanish sharp ribbed newt)
5. Pachytriton labiatus (paddle tail newt)
common names are not always reliable
All these animals can be incorperated into fairly simple set ups so don't worry about having to get an expensive filter or elaborate decorations. Most of the afore mentioned animals, except for the Ambystoma sp., will be perfectly happy in an aquarium with a single rock potruding from the water for land.