totally depends on your cicumstances and the individual personality/needs of the cat what is appropriate. My older cat for example, I had to get a house cat from the RSPCA as I don't have a garden, however my area is quiet, my road doesn't lead anywhere and as there are no gardens all the kids play in the road, therefore pretty much everyone who drives round here does so slowly therefore the chances of an accident are quite small, there's shed loads of cats round here and I've never seen an accident. She's very hyperactive and I decided after a few months of having her that being cooped up in a house all day probably wasn't the right thing for her, so I gradually introduced her to going out, had her out with me on a kitty lead which she hated! Had about a yr of her being out and about quite happily then a few months ago she came home with a massive wound, I think a fox had tried to kill her but she's a double hard b@stard so she'd managed to get away, she had stitches and I was v worried about her, thankfully she's OK now but she's still very wary of going outside, now she only goes out when I'm outside and then she won't go further than just down my road, perfect arrangement for me, just sad it had to happen like this. Now I've just got my new kitten, as she's only 8 weeks obviously she won't be allowed out just yet, but I'm hoping she'll take the lead from Mitt's and just stay close by, fingers crossed anyway!
I do feel like some cats just need to get out, Mitts certainly did, I tried everything I could to keep her entertained indoors, she had loads of toys, I'd try to play with her, but basically all she wanted to do was hunt and the things like wind up mouses I got for her to hunt indoors just weren't good enough! So she sits outside and stalks the pidgeons, thankfully she's a rubbish hunter and the most she's come in with is a feather
One of my friends has a pedigree cat and she won't let her out cos she's scared she'll get stolen (quite likely in our area.... soon as someone clocked she was worth soemthing she'd be gone) but she's a very docile kitty, all she ever wants to do is sleep so she's perfectly suited to being a house cat.
Basicallly I think you need to assess your area and what's going to be best, speak to other people near you who have cats and get they're experiences, find out where the cats play etc, then when you've decided if they're going to be a house cat or not, then you need to choose the cat appropriately, let the rescue centre or wherever you get them from know whaty you've decided and they'll help find a cat that's suited to the home you can provide them.