The schefflera is much easier and much more forgiving, but if you're embarking on a bonsai journey it would be nice if you had a temperate tree to go along with the scheff. Maybe something really vigorous like a Chinese elm or a Cotoneaster would be nice. If you're set on a maple, try Acer buergeranum (trident maple). Most people will think it's a Jap maple anyway.

Al

I second both the Cotoneaster and the Acer buergerianum.

The Cotoneaster will probably give you a more believable "bonsai" sooner....
but the Trident Maple is so vigorous that it's a great tree on which to practice your
pruning, root-pruning, and re-potting technique.

Josh

When you mean temperate then you mean fitted for zone five?

i just looked up cotoneasters on google and that is exactly what you meant

i've had a schefflera before and I bought a sunset japanese maple for my mothers day for her outdoor garden but was thinking of buying one for bonsai but a cotoneaster looks very interesting

Check this link. This site has guides on Bonsai for beginners and teaches you about which tree to grow to start off!

I'd say Juniper, but if you really have to choose between the Hawaiian and Maple, i'd say Maple. Again the site has info on Maples and stuff so you'll find everything you need there!!!

Maples are easy to grow because they are genetically vigorous, but very difficult for beginners to keep looking good. I wouldn't suggest a maple for a beginner.

Al