Here are my two cents about the ROMs, stock or custom.
First off, with the stock ROM, if you have a bug, or a failed update or something that goes boom what are you going to do? VZW support won't/can't do much. They seem to resort to bring it to a store and we will either get it fixed or replace it with a REFURB. If that doesnt suit you, your only other recourse is the fine people around here. More than likely, you are gonna walk away with a working model with the help of these guys. I consider that a minus for the stock ROM, and a plus for the custom.
With the custom ROM the guys around here know it backwards and forwards. They can fix things easier and more to your satisfaction if you can follow directions.
With the stock ROM, you are FORCED to use what ever they want. You cannot chage your default search button to google or yahoo or whatever. You have bing and you'll like it. With a custom rom you have google pre installed. Enough said.
Also, the custom roms do not have all the other bloatware that VZW puts on. no bing, bing maps, and a bunch of other crap (sorry I am really tired cant think of the others). You will get more out of your phone just on not having all those preinstalled apps start up all the time and bug you.
Dont like the way your status bar looks? With a stock ROM, your stuck with it. With a custom ROM (with root of course) you can flash any one of a number of options to suit you.
Don't like that your battery drains so fast with a stock ROM? Your outta luck. With a custom ROM, you can flash a custom kernel that can be undervolted (thus using less juice) to try and help a charge last longer.
You want something that you dont have to do anything with? Then stock is for you. You will have your quirks, but usually it works and you never have to think about it. With a custom ROM, it takes just a little bit of work to get it just right. Now that isnt to say that ComRom doest just work right after a flash, it most certainly does. It is just the little tweaks to help it along (battery life, look and feel). But on the upside for the custom rom on this point, MY phone is just that, MY phone. I may have the exact same thing (ROM, Kernel) as sharkie, but guess what? Mine looks better, his has a better battery life....they are different phones altogether. I think it is a plus.
Time for bed. I will vote for Custom every time, but then again I also have an addiction to this thing. You get out of it what you put in.
PS: If you are worried about flashing a ROM and ruining your phone, really don't be. With the proper READING and a little patience, you ALMOST cannot ruin the phone for good, and if you do hit a "brick", these guys can get you out of a hole. I have seen them spend all night fixing a phone of someone they never met, never will meet and they have no vested interest in whether or not the guy has one. They are just that good, of people.