I think the advice above from
@nwhornet and
@Simon G is spot on! I like nicely made things and so I have what I consider to be something special but I equally love my little picos with a clone rta on the top that is a fraction of the price. I also like a couple of small pod style AIO’s that were cheap as chips.
As said if you want a new mod then go for something you like the look of as it will pretty much do the same as anything else. If aesthetics are important then go for that.
I think, but could be corrected, that the gap between RTA and RDA is quite negligible these days flavourwise. For testing your flavours I guess the rta would be far less hassle as you can change out much more easily.
Stock coils for mtl are ok from what I’ve tried. They do the job and some give a decent flavour. Rebuildables I find far superior as, was also mentioned, you can tweak them a lot more. I find they also cope with more types and flavours of juice than stock coils do.
There is a mass of info in the mtl section for all things mod and rta/rda and plenty of pics to give you some ideas on what things look like.
There will always be the next best thing and there will always be something that is claimed to be amazing. I’ve loved some and just not got on with others. Clones are a good start as they are cheap and let you try things more easily and if you really like something it’s perhaps worth getting an original of that clone to support the makers at a later date.
Get a few different wires to try like a 27-28 kanthal, some ni80 wire and perhaps some mtl Clapton wire and have a play. Get some muji and maybe a cotton bacon or cotton gods and play with the cottons too.
It’s all very silly really but fun if you want it to be.