Speed: Probably Acela for now, at least during peak traffic times. But LimoLiner marketing consultant Lori Cohen promises that the service's drivers and attendants will be working to use satellite and Internet technology to better anticipate traffic and avoid it.
Schedule/locations: Acela. Without weekend trips, LimoLiner's three-times-a-day schedule (reduced already from four times a day) is too limited for the leisure traveler. And even though LimoLiner gets you slightly closer to the action in midtown than Acela does by going into Penn Station, Amtrak's three departure spots in the Boston area (South Station, Back Bay, and Route 128) beat LimoLiner's two (Back Bay Hilton, Framingham).
Food/drink: Acela. True, LimoLiner's offering is free, plus fresher and better-tasting than anything you can get on the train, but Amtrak offers many more options, including one that many travelers would find crucial: alcohol.
Service/friendliness: LimoLiner. What better service than having an attendant to bring you (free) food and drinks? Acela does this in first class, but that's another $50 each way.
Other amenities: LimoLiner. Both offer electrical outlets to power laptops and other devices, and both have music channels, but nothing beats movies for killing time, and LimoLiner played two decent, recent ones. (Headphones are provided, unlike on Amtrak.) LimoLiner also provides wireless Internet or service through ethernet cables, which are available in case you forget yours.