RAR is the most convenient for creating split files.
7zip split files are a pain for most users as it gives the first file the extension of ".01" which 7zip does not always register as a file-type.
I have to use 7zip on my site, and I don't like the lack of recovery-records.
RAR is the format of choice for secure/recoverable files (especially when the files are large).
Please note, if you use the newer compression modes in 7zip, to always save as a 7z file, never a ZIP.
7Zip unfortunately allows incompatible compression in different containers.
As ever I will recommend the use of the CoraCDN for distributing large files.
If you have the space, but not the bandwidth, this is your best bet as you keep control of your files.
I use it regularly, as do many DJs/producers, to make sure large/popular files are always available.http://www.coralcdn.org/overview/Upload/download sites.
You can all avoid ads on these sites, by never even visiting them, and just pasting the DL into "MiPony".
The site also lists more Upload sites than you ever knew existed !
If you don't like the ones you have seen, then look for a better one here.http://www.mipony.net/features.php
(As usual say no to all the extra crap it offers to install).
In the main, I would agree with the comments on Mediafire.
Mediafire is fast and also supported by MiPony, so you can still avoid any ads.
BUT be warned, Mediafire will not notify you if one of your files has been blocked.
You will only know when someone trying to get your file complains.
I regularly recommend the MyOpera community sites for storing files, as the sites are ad-free and unlimited in speed or bandwidth.
The limit is 2GB total, and files have to be under 60MB-ish.
For most people this is fine, and obviously you can split archives if needed.