If you use a trailer its pretty much the same as using a pushchair (stroller) and indeed some double up (I wouldn't get one that doesn't) - you'll get a 5 point harness, a seat that reclines and you can get head cushions and the like too.
Of course a trailer may not be practical in your circumstance (though I'd be surprised) but if it is it also helps deal with the problem of all the other stuff you want to carry when going out with a small child.
One other option for practical as opposed to more recreational use is a cargo bike or trike of some sort - I'd've loved one of these a Nihola or a Christiana Trike - in which you can put the same seat/carrier you'd use in a car 'til they're of a size to sit up. There are also Dutch cargo bikes that can similarly be equipped with benches, rain covers, etc. But I'd probably still have wanted a trailer too for longer rides (-: