I'm not sure if you've followed the links, but a brief potted history...
Marvel US began releasing their bimonthly Transformers comic in 1984, originally intending it to be just a 4-issue mini series. It did really well, and so a regular monthly soon followed. In the UK, reprints of American comics were common, and so the Transformers UK comic was launched in Sept 1984, on a fortnightly basis. Each American comic was split into two parts, so that the first 4-issue mini series actually gave enough material for issues #1-8 of the UK comic.
Still with me? Anyway, what with different publishing schedules to the US, the UK Marvel team realised they'd need to create some of their own material for in between the US reprints. Initially these were written with no regard to continuity, but pretty soon main writer Simon Furman was able to intertwine his UK stories so that they not only fit into US continuity, but often helped make it more understandable, filling in plot holes, developing other characters, answering questions etc etc. The Marvel UK comic eventually went weekly (and then fortnightly again) totalling 332 issues before it finished at the end of 1991.
So, in terms of story continuity, you're best off with the Marvel UK one - you not only get all the US stuff, but lots of FANTASTIC, exciting stories about time travel, transformer gods and other cool stuff that only the UK saw!
Regarding GI Joe - Marvel US produced a truly terrible 4-issue mini series called GI Joe Vs. The Transformers. Not only was it pure hack work, it also didn't actually tie in with the continuity of the main comic (e.g. Ravage was alive and well, as were Thundercracker and Skywarp - all dead/presumed dead by this point). It definitely didn't make sense in the UK continuity, so was skipped over in the UK reprints (it was eventually reprinted years later as an "alternate reality" thing). But, Marvel UK did decide to do their own GI Joe (Called Action Force in the UK) / Transformers crossover. This was far superior, and featured the return of Megatron (well, briefly anyway!).
I really can't stress how much you'd be missing out on if you just went with the US stuff!
Are you planning to actually get the original comics? That's where you might come a little unstuck - the 80 US issues are quite common, less desirable and easy to find pretty cheap (save, perhaps, the first four and the last few). The UK comics...well, not only are there 332 of 'em, but you're also looking at crazy prices for some of them (a Near-Mint #1 went recently for £72 on ebay...what's that? Around $140?). As a dedicated Marvel UK fan, I'd of course say they were worth it, but others might not!
So, what to do? Well, MOST of the stories from both the US and UK comics were reprinted into nice trade paperback graphic novel collections by Titan. Frustratingly, not all the UK comics were put in continuity order, but it's not too hard to work out which fits where! (I'll happily help!)
IDW - the current TF comic publisher - have also reprinted some of the UK material; I haven't looked into them yet, but I'm guessing that's also a good way of getting hold of the stories.
As a beginning, you'll want to pick up the TPB "Beginnings" and "New Order", which contain #1-12 of the US series.Don't be put off by some of the less-than-stellar art, or occasional rubbish dialogue...it gets better, trust us!
Forgive the essay, but as you can see, I feel passionately about spreading the Marvel goodness!!
