For a beginner Bonsai Tree grower I would recommend the Bonsai Dragon Willow Tree from Amazon or the Rock Juniper Bonsai Tree or the Dawn Redwood Bonsai Tree.
Those are all good Bonsai Trees for beginners who're just getting started with growing Bonsai Trees.
I started with the Bonsai Dragon Willow Tree from Amazon and then worked my way up to other Bonsai Trees.