Not a lot to choose between M and T, similar price delivered and complete with wax, frames and queen excluder. M have angled wood runners, T are plastic. If you want to upgrade to metal T's are easier to replace. T floor a little less robust than M, and supplied drawing pins for the mesh don't last long, you will need more nails or small screws. Some prefer one over the other, sometimes after getting a first example with more than average knots. Both are adequate as a starter but expect to need a few tweaks to get closer to what you actually want.
Seen fewer Caddons, they don't do an exact equivalent, including frames, wax and QE will put the delivered price above M or T. Somebody is always selling on eBay, but you have to check exactly what you're getting and you know the larger makers will answer the phone if you need them.
If you can wait for M or T sale time, or pick up at a show, you could substitute variants for a modest increase in cost, such as deeper roof, better QE, extra super etc. Big plus of the standard budget offering for a starter's first hive though is you get everything in a box, exactly the right no of frames, nothing you have to rush out for. Not so great if you're not confident assembling, but you pay a premium for that from any supplier.