This is the last time I promise..
Its between the following:
The things I don't like about sidekicks is you can't download more than 10 ringtones and you can't just download ringtones from sites like funformobile.
Another thing that isn't too important but I'd like it if the persons ringtone and text messaging ringtone were the same.
As for the G1 vs Behold, the main difference is going to be physical keyboard vs touch keyboard. That is primarily personal preference and no one will be able to tell you which one you'll like better.
I say go for the G1 since it has more potential being open source (meaning anyone can develop any program for the phone and make it available to you via the Market). The Behold does have a 5 megapixel camera with flash, and is a lot smaller...
Just go into a store and play with both of them. They both have different types of touch scree...
All phones that I know of allow you to set a set ringtone that is universal for all text messages regardless which contacts send them.
If you know of a way to set a specific text message notification ringtone for the G1 or any other phone...please let me know. From my understanding it can't be done yet.
My gf and my best friend both had razors and if you set a certain ringtone for one person's calls it is also their text message ringtone.
But by the list you provided...
I have G1 and another rep in my store has the Behold.
G1 = More for internet use and apllications.
Behold = More for looks and operates better as a phone.
Generalizing a bit.
Rumors are the Samsung T929 Memoir launches on the 18th of Feb. 8MP camera and Android Market.