For the average cruising boat, I fit my running rigging with whatever double braid I can get a good deal on. Sampson is my favorite name brand. New England Ropes is another good one. There are some generics. All the ones I have worked with are pretty darn good. I am fortunate to have a local shop that sells me double braid at about 1/5 the price that Worst Price Marine sells it for. There are a number of on-line suppliers that sell it cheap by the spool, but for rigging a single boat, a full spool of one color is not going to be what you want.
Strand oriented UHMWPE lines, like Dyneema, Spectra, etc, have excellent strength per size & weight, but they are kind of slippery, so you need to tie them off a little differently. Special knots & splices exist for use with these expensive specialty lines. I only use that stuff on serious high end race boats. If the hull isn't made out of carbon fiber, I'm probably not going to be reaching for very much Spectra. That stuff can be a little dangerous too. I have seen it cut through a gunwale after jumping out of a snatch block while being fed out quickly.
Halyards need to be strong enough & they need to fit. Low stretch is nice. Sheets should really be be comfortable on the hands. Here you might want to choose the diameter, for handling ability, more than for strength rating. In many cases, a 1/4" jib sheet would be strong enough, but I will still want 3/8" line, so that my hands don't feel the bite as much. Slick handling lines are not good for sheets either. I avoid Spectra for sheets, unless we are talking about something in the TP class or above.
Stretchy lines, like 3-strand, are mostly used for anchor lines & not for running rigging, although, on older, low performance boats, it sometimes gets used there too.
For a Capri 22, I'd shop around for some cheap double braid that feels good on the hands. End of story.
