I can't really comment too much as I haven't had too much experience with a whole lot of different prams. We have a Mountain Buggy Urban Elite which is a three wheel pram. I love it. Very easy to manoeuvre. I've tried it on the beach and it is great when on the harder sand, on soft sand it was a bit harder - but I guess all prams would be hard to handle on soft sand? They are a bit bulky for town/malls etc I think but I still use ours in town. I think my Aunty had to get a smaller four wheeled pram only because a bigger three wheeled one wouldn't fit in her car. Mountain buggy's are a bit pricey new but we got our practically new one off TradeMe for less than half price.
I think that three wheeled prams would be better if you were going to do jogging/running/long walks as they usually have bigger wheels and the front wheel can be fixed so that it goes straight all the time.
Four wheeled prams are usually smaller so might be better if you do a lot of shopping?
Sorry - probably not much help but that is my two cents
Good luck!