Once you start building your own coils Razz you likely won't look backwards. It's so cheap, and you can tweak the flavours and vape you get by making such small adjustments to your usual build. Coil size, height in chamber, amount of wick used etc. As someone who used to roll my own it has nicely replaced that fiddling I used to do making the rollies. I also love the fact that for about £10 I have enough wire and cotton on hand to last me about a year in coils no matter what new laws they bring in. For me with the Subtank Mini (as a mouth to lung vaper) I have found the sweet spot to be my own coils at 1.6ohm and between 9-12 watts and on the smallest airhole (slightly closed depending on the juice). The 1.2ohm coils will burn through the juice a little bit more but you'll get a great vape and flavour from them for sure :-)
One tip - take a good look at how the coil is suspended on the RBA out of the box before you change it (it has a 0.5ohm coil already fitted IIRC and you'll likely want to swap that out). I have found that the best position for the coil (for me) is suspended half above the posts and half below, which is where mine was out of the box. This position provides a great vape and flavour, but if you go any lower than this then you get spitting and a harsher taste. I'm no expert at this for sure, but after a few weeks of fun and fiddling I am now building my own coils and wicks that provide a consistent vape. It's a fun journey if you are in to it, so enjoy. If not, you have the stock coils anyway :-)