whichever hosting site you do use, it is essential that you realise you need a specific type of file systemto actually download and upload your data, or to move your data between different tree building software, you need GEDCOM ,
http://en.wikipedia.org/wiki/GEDCOM
which means you can download your research and your tree in it's online format from say ancestry or FMP and then transfer it to a software on your laptop for editing or to add photos that you may not want online. It's not the same as simply downloading text, as a family tree builder contains all kinds of text and layouts, as well as having the ability to interpret the various genealogical records and link them to your ancestor.
Family Tree Maker is expensive but it matches ancestry.co.uk perfectly and is ideal. You can build your tree on ancestry without having a subscription, then when you have compiled it, take out the free 14 day trial and then add the primary and secondary source material to your individuals which would remain there whether you carried on your subscription or not, alternatively, you can use any tree builder software BUT you would not have the compatability to link the records to your individuals, unless you bought all the relevent certificates and scanned them to your photos say, there is not much else you can do.
If you wanted to send a CD version of your tree to sdomeone else, it is useless to them unless they have the software to open it however,