Snacks
To be honest I understand the need to set your self apart from the masses. I also believe that trying to go with an e-mail provider who is trying to reinvent the wheel is not a good option. I use gmail however my e-mail is not @gmail.com its @wisetechfly.com ....you could purchase domain name of your choice and then link it to google groups. So if your domain was
www.ilikedoritos.com then your e-mail would be
snacks@ilikedoritos.com.
Also with google you can use Imap which is better then POP. This will allow syncs to occur not just a one way push. Meaning Imap keeps messages on server and allows for multiple devices to be synced with current e-mail whereas pop does not. I truly believe this is the route you should take. Also to answer your question on what e-mail clients I use: Outlook 2010 configured with my g-mail Imap account and Exchange account for work. I can tell you the crappy interface problem you are experiencing will go away if you just setup your accounts to download in Outlook. This also will allow you to make backups of your e-mail for safe keeping.
I checked the internet for other mail providers and I compared the options vs what G-mail/Yahoo offer and I really don't see anything that would make me switch from g-mail I gotta give it to them they know what their doing.....also I have never ever not once lost an e-mail with g-mail which is very important to me at least.
Final thoughts:
E-mail is just e-mail does it really matter how fancy it is? It should do what it is designed to do and that is pipe a message to you. I would setup a mail forward from your inbox.com account to your new gmail account.
If you need help setting up the google groups please let me know I will configure your mx records and everything to get it working.
Thanks
Stephen