It depends on the relationship you can develop with your clients. If you have good loyalty and don't need new clients, microcurrent will keep your clients rebooking for treatments because the results are short term.
Radio frequency creates cellular change and gives results which will be noticeable very quickly and which will last, fading naturally as part of normal ageing. It depends which machine you want for yourself! I'm a radio frequency girl. I never bother to use the microcurrent option on one my other machines - I never even mention it to my clients!