Neither, Tom. I personaly dislike bateries built in the devices. I know it's a trend that goes hand in hand with consumer philosophy, powering the industry and keeping our jobs. But it shoulden't be this way.
The LiPo battery will sustain 500 - 1000 cycles, depending on its use, which will give 2 years+ to a frequent user and between 3 to 5 yeares to the moderate one, which is a fair deal. Non the less, leaving moderatly used battery unatended for prolnged time periode might finish its life prematurely. Furthermore, the battery is usually just taped to the motherboard, so if or when it inflates, it ofently damage the board and/or display. Dough the tablet computer is rather obsolete after 5 or 10 yeares, a top line detector will still be quite useful and a good performer. Yes, replacing the battery is usually not a big deal, but opening a water-proof housing might be tricky. That is why i personally prefere detechable batteries, modern or old fashion ones.