It mostly depends on the TV itself. Its screen size, how much it needs to scale/stretch the picture to fill it, how good is at it, what type of input has...
Your average crt will look worse than your average lcd, not just because they tended to be blurrier, but also because they very often lacked options for better inputs like component (I guess in PAL regions it was much easier to find scart input for RGB). Of course, the crts have an advantage in higher screen refresh rate, which makes movement on screen cleaner... Of course crts are getting older all the time and as said above that also matters.
That's why when talking about crts people tend to talk about specific types.
But yeah, the less they scale the better they should look. It's also a matter of taste, some people prefer the blurrier crt experience, others a sharper one, and some don't pay attention at all.
Now, 480p will always be better than 480i. There's no much more to say there. The screen refreshes all at once instead of only half, and makes it look better.
The type of input matters a lot, since the one most we experienced back then, composite, is terrible and only better than RF on my experience (and only because RF is its own can of worms).
If you want a sharper picture out of your Wii, if you are on 480p one thing you can do is to remove the deflicker filter.
Pretty much all gc/wii games come with a filter to avoid flickering on interlaced resolutions, but they are still applied on progressive scan. Disabling it with usb loaders you get a sharper picture.
Beyond that, I'd say that the need for external help for old hardware it's more seeked as time goes on.
Scalers are becoming more and more sought after and they can do great work but of course they are more expensive solution... Yet I think they'll be the best way to "future proof" old systems working with modern displays.
Although I could not recommend the currently standard giant tvs, really. Even with current content I don't feel they look great, lots of pixelization and artifacts, unless you really can have native 4k on everything.
