Java Sparrows
These are fun to keep. They rear young on seed, and require slightly bigger nest boxes that finches.
There are now several mutations including silvers and fawns (pic).
Very shy birds however and seem to take forever to raise chicks.
Parakeets
You can start with one of many species, Lovebirds, Kakarikis, Splendids, Cockatiels, and so on.
These are all fascinating birds and all these species come in mutations.
Parakeets require more heavy duty mesh and woodwork in fights.
I kept lovebirds for one season and they shredded much of the panels of tannalised timber to fill their nests.
Cockatiels can look magnificent but unless you get a hand tame one they can draw blood from you easily. Ironically they can be kept with other birds and never seem to harm them.
Kakarikis are the best option if you fancy keeping bigger birds than finches. They have a placid temperament and will 'hand tame' to owners' if owners gives a little time to them.
They breed freely and because they are originally ground birds from NZ they do not require massive flights. They enjoy climbing up and down mesh.
The only downer is the sound they make-my neighbour asked me one day-which of your birds makes a noise like a ' goat' ?