Just anything man. It seem like even the budget bikes are going to have 21 gears and in my experience it isn't until you get near the $1000 mark for bicycles that very much about the quality of bike even changes at all.
I think the type of bike is more important than the brand for newbies. I prefer a street/ mountain hybrid bike.
The tires are wider than a street bike but narrower than a mountain bike. I find they are the most durable and honestly, the brand name at lower to mid-range price isn't as relevant as the manufacturer would like to have you believe.
Sometimes I feel as though they are all made in the same factory and they just put different decals on the brand-name ones.