I've done a fair number of psychedelic research chemicals such as exotic tryptamines like 4-AcO-DMT and 5-MeO-MiPT, and I dabbled with 5 and 6 APB (empathogens), but I've generally stayed away from other types of RCs. I'm motivated by curiosity to experience new states of mind on new substances, but I haven't felt the need to experience the nuances of different exotic stimulants - to me, if I want to party and need some quick energy, I'll do a line of coke; not interested in exotic stimulations like 4-FA or a-PVP. However, I imagine most users of RCs, whether psychedelic or empathogen or stimulant or depressant, have the same reason - curiosity about experiencing different substances.
I'm not sure what type of drug experiences you're looking for, so I can't really suggest what RC is best to try for you. I say just pick one you have access to, read about it on here, Erowid, or even Wikipedia, and if it sounds interesting, give it a try. Be safe!