The brand makes little difference, they are all made in the same factory in Taiwan or China.
Find your local bike shop and look at the brands that they stock. You can chose an appropriate style of bike , probably a "comfort" or "hybrid" style. The comfort style bikes usually have MTB size wheels and the the hybrids have larger diameter wheels. It makes little difference unless you are small, then a small wheel is preferable.
The support you get from your LBS is important. They will ensure that the bike fits you, that it is well assembled and will be on hand to service the bike later.
Make sure that the bike can accept a proper luggage rack that bolts to the frame (for the child seat).
If you want the best value then pick a good time of year (Jan-March), don't worry about getting this years latest model, negotiate on extras such as helmets, repair kits, spares and other accessories, child seats etc rather than cash reduction.
Don't get a bike the wrong size just because it is good value.