In my opinion, the best option is a convertible from Lenovo or a subbrand thereof. EFI is never a problem with RPM distros, it's a problem reserved for old conservative distros. What is a problem, is that the internal storage of a tablet or convertible, doesn't follow the standard nomenclature of storage, and if a tablet is preloaded with Windows 8, you won't be able to dual boot, because Microsoft makes sure that it occupies 4 partitions on the volume, so that it's impossible to make the system work with an extra one, well... it's not impossible for linux, but then Windows won't work any more. So you have to make a choice, or get a tablet capable of virtualization if you want to also run windows on it. Most tablets come with 4 GB of RAM, so virtualization is not going to be fabulous, except if it's an Atom tablet, which means the Intel Celeron N series. Those are about as fast as a late Core2Duo chip, so no slouches by any stretch of the imagination in linux, but at that performance level, they're pretty "office and browser-only" in Windows. These chips also have very limited graphics capabilities, with only up to 4 ROP's on the iGPU's, but that somehow suffices for CPU-focused games that don't require much graphics power, like CS:GO, which runs great on a Celeron N2940 based tablet in my experience.
Another really important thing with tablets is the quality of the touchscreen. Many cheaper models have pretty bad touchscreens. Even very expensive models, like the Surface 3, have pretty bad colour rendition and aren't worth much. There again, Lenovo and it's B-brands, offer the best option, with pretty nice IPS screens that do not include a digitizer plane, but have very precise and sensitive capacitative layers, that allow for actual note-taking with a very thin passive stylus. What you lose in comparison to a digitizer plane and an active stylus, is pressure sensitivity, but if that's what you want, the only good solution is a Wacom digitizer screen anyway, because those are the only ones that actually work as they should and still have a decent image quality.
If you want a full-on PC with a touchscreen, wait another year, two generations of Lenovo Yoga convertibles down the line, those will have become the most popular laptops in the market, the new Yoga's are pretty good already, but rather expensive still and sometimes a bit flaky in certain aspects, but they're getting better all the time, and in two product generations (which is about 1 year), everything will be ironed out, and the prices will come down because more people buy them.
Especially for linux users, touchscreens are great, because they usually come in higher resolutions but are relatively small in surface area, and that's something that linux can handle, but Windows absolutely can't, because GUI scaling in Windows is just abysmal. I use OpenSuSE 13.2 with Gnome 3.14 and kernel 3.16.2 right now on a B-brand Lenovo Celeron N2940 convertible, and hacking the EFI was pretty easy (only about 40 minutes to solve everything), and it works great. The new Gnome multitouch gestures are great for productivity, as you can swipe from desktop to desktop with 4 fingers in all directions for instance, and with the new HighDPI control, you have full stepless control over scaling of individual GUI items, like you can scale the windows in a different way in comparison to the fonts or the GUI differently in comparison to the applications, etc... it's crazy good.
Also next year, I expect Apple to come out with an x86 tablet or convertible, and that might also be spectacular, because in general, Apple does this kind of thing right.
So if you can't wait and have to play with one right now (like I had lol), get a cheaper quadcore Atom-based one (Celeron N series) that's still unlocked enough for linux and has a nice touchscreen enough, so that it's nice to work with, but doesn't ruin your budget.
For the next generation of cheaper x86 tablets, the Intel Cherry Trail that's coming out soon might just be the thing, or the next generation Broadwell in low power variants. Fact is, that Haswell chips are not good for tablet use, because they throttle like crazy, and you end up paying a lot for a device that doesn't perform proportionally to the steep price. For instance: you can play CS:GO perfectly fine on a cheap quad core Celeron N tablet, which peaks at 7.5W TDP, but you can't on an i7 Surface 3, which also requires a cooling solution with vents, because it throttles like crazy, and the Celeron N tablet doesn't even have vent holes that are a hazard for tablets. This technology is still evolving, in a year or so, much better devices will be available. It is great though, I'd rather take a 1080p or 1440p touchscreen than an 8k non-touch. Touch is great for getting stuff done quickly and efficiently, especially in linux, and probably in the future also in OSX. With all the years of embedded linux touchscreen experience (well over ten years) and the entire Android experience, it's also normal that linux has the best implementation of touchscreen and that it runs the show. That's also a reason why Lenovo will probably have the best implementation for years to come, because they are the most linux-oriented manufacturer by far.