I'd say stick with cingular unless you're getting a better plan with verizon. Verizon is a BREW carrier where as Cingular is J2ME (java). Since verizon is BREW there aren't as many developers for content and the content that is provided (as far as i can tell) is "closed garden" (has to be approved by the carrier).
Cingular is open garden so if you want to download games and ringtones it's much easier to do so. Plus cingular is GSM so its simpler to upgrade your phone, just swap the sim card. with CDMA carriers (like verizon) you have to call up their customer support.
should you still decide on verizon i'd say go with the E815. Its motorola so the OS is much better designed in my opinion and it has a PC sync feature. the samsung sch-a950 didn't really impress me that much. But both phone are very simlar and its really just a judgement call on your part tho. i'd say have the people at the verizon store boot up one of each so you can mess around with the menus a little before you buy either.
hope that helps
I want to get a new phone with a MP3 player. I'm currently a Cingular costumer, First, Should I switch to Verizon. Second, if I do I want either the Samsung A-950 or the Motorola E815. I like both phones, but don't know which ones I should get? Any Ideas?