Having had both, combos and seperates over the past 25 years or so...I'd have to say that seperate heads/cabs is a better way to go.
For combos, I've had a little GK combo and old Peavey combos way back when, and a Hartke Kickback, BAM210, Carvin RC210, Eden Metro.
For amps/cabs the list is way too long to mention here...but with amp/cabs you can get all of the benefits of combos but more options to mix and match down the road. Depending on what you get for an amp and cab, you can get just as portable (if not moreso, as decent combos are still quite heavy).
There is a thread out here about "small rigs" that will give you a lot of info about seperate heads/cabs that should point you in the right direction. Any of the combos I listed above are great little combos...with the BAM210 really being the cream of the crop...but heavy (though it does come with it's own wheels and cart-style handle).