We're not about to launch into a voting thread so . . . let's not.
Pick one. Get it right the first time. Most of the bigger players will do a decent job. Sometimes it gets down to small details that are appealing to you so shop around by checking out the UIs and see if you can get someone on the phone in customer service - for starters. :)
You might even consider becoming a reseller and transfer everything to your own shop - you have a complete control over it now. No worries.
Best wishes,
humhum