I (hypothetically) own about 15 websites, each one with its domain,
with about 30 programmers that works on different parts of them.
I need to choose a reliable hosting provider that allow me to easily
manage all of them in a single account/control panel.

Id est I want to know the biggest hosting providers that provides a
single account/hosting plan with these requisites:
- multiple domains with email support (support for atleast 15 domains
w/email, each domain pointed to different directories under the root
of
my main FTP account)
- multiple FTP accounts (for my programmers, with access limitable to
specified directories or subdirectories)
- under $50/month. VPSs (like www.anywherevps.com or
www.websitesource.com...) usually costs more and are focused to
hosting reselling, that have separate control panels for each domain,
therefore are usually not good for me
- bigger, in Google PageRank and Alexa Traffic Rank, than
WWW.HOSTGATOR.COM or WWW.WEBHOST4LIFE.COM, that are the biggest I was
able to found till now. See details here:

__

WWW.HOSTGATOR.COM (Unix)
 Google PageRank: 8/10 (higher is better)
 Alexa Traffic Rank: 1376 (lower is better)
 Alexa Online Since: 22-oct-2002

 Multiple domains: unlimited
 Multiple FTP Accounts: unlimited
 Price: $9.95/month
 Live chat support: yes
 Source: http://www.hostgator.com/shared.shtml

__

WWW.WEBHOST4LIFE.COM (Windows)
 Google PageRank: 6/10 (higher is better)
 Alexa Traffic Rank: 6030 (lower is better)
 Alexa Online Since: 3-oct-2001

 Multiple domains: unlimited
 Multiple FTP Accounts: 300
 Price: $19.95/month
 Live chat support: yes (sales only)
 Source: http://www.webhost4life.com/hosting.asp

__

Can you find bigger ones that respects all my requisites?

hi,my choice is bluehost.I think it is wanderful.you can see
details:http://www.bluehost.com.
Hope that can help you.

1&1 is also good choice.And you can see details
at:http://order.1and1.com/xml/order/HostingDev;jsessionid=F5670054877C4FADE31077E95E0DC224.TC61b?__frame=_top&__lf=Static.

the price is wanderful, $19.99/mo.
Communication Tools 
Chat Channels  10 
In2site Live Dialogue   
1&1 E-mail Marketing Tool  

Core Features
Web Space 250 GB 
Monthly Transfer Volume 2,500 GB 
FTP Accounts  50 

Private Domain Registration   
Manage Unlimited Domains  

E-mail Features 
E-mail Account  3,000 
IMAP & POP3 Supported   
Mailbox space 2 GB 
E-mail Aliases  10,000 
1&1 WebMail   
E-mail Forwarding   
E-mail Auto-responder  
Catch-all E-mail Addresses   
Spam Filter  .

Thanks adixm for the suggestion!
Bluehost is very big with Google Rank: 8 and Alexa: 818 but it
supports only 6 domains.
1&1 is a Unix hosting provider less big than Hostgator, with Rank:
(null) and Alexa: 4364.
Anyway I didn't know them therefore I'm very grateful to you for your informations.