If just starting out I and want to be cautions I would suggest something with a 510 pin (Broadside or VCM X1), its just one less thing to worry about. If you do choose a hybrid style connection please make sure to use an RDA with a protruding positive pin and as a general rule of thumb I would avoid using tanks on mechs. Also, if you are just sticking your toe and don't plan on using ultra low ohm builds you can find incredible deals on authentic mods from back in 2013-2014, granted at some point you may outgrow these devices, and will most likely be limited to 22mm attys with 3 post decks or smaller post holes. But then again you can find some great deals on "Competion RDAs" from the same period and in my opinion mechs work well enough with a simple round wire build. Vindicator and SOI X series mods are wonderful devices, but personally I never recommend a hybrid 510 connection for someone just starting out, especially if they will also be learning how to build their own coils.