You really need something like the Innokin Ares 2, or the Vandy Vape Kylin mini v2, Digiflavor Siren v4 etc because you really need a single coil RTA with a large enough deck to learn building on.
Smok TFV8 Baby Beast RBA Head & Big Baby Beast RBA Head
^^^ you can buy an RBA head for the V8, but it's dual coil (very difficult to learn) and the build deck is horribly small..
But I would definitely get an RTA geared towards new builders (single coil with space to work)... certainly those I've recommended aren't the only single coil RTA's out there, but it's been a while since I've purchased an RTA, and don't know what all is available right now to recommend.
If your truly wanting to vape higher nicotine levels, then you need to stick with gear designed for MTL vaping...