I have a
Linx 10 and it's great. Has HDMI out and unlike the iPad you can choose whether to duplicate the display on the external screen or extend instead, so you can play a HD movie on a HDTV while using the tablet to check your email or browse the net. When using it as a PC you can run it as a dual monitor display, being able to drag folders etc from one desktop to the other, as you can with any dual monitor PC. It supports all different screen resolution so you can run a HD monitor alongside the tablets own display.
This model runs Windows 8.1, full Windows 8.1, so you can install any PC software you want. The
newer model runs Windows 10 but charged through a micro USB.
The W8.1 model can be upgraded free to W10 but I tried it and went back to 8.1. I love W10 on my PC but on a tablet W8.1 is far better IMHO. The swipe gestures make it far quicker and easier to use. Even installing Chrome for web browsing lets you swipe right to go back to the previous page, far easier than hitting the tiny back button. It also has a micro SD card slot so you can easily add more storage.
The new model does have two standard size USB sockets, which is nice. The older one has one micro USB. They supply an adaptor with it.
There are keyboards available, from Linx and third party but I haven't tried any so can't really comment.