This Brief studies comparatively the different 8-phase feedforward-coupling (FC) ring voltage-controlled oscillators (FC-RVCOs) in terms of their oscillation modes, oscillation frequency and phase noise. Among the 3 feasible topologies, the one with sub-feedback loops containing 2 Direct-path inverters + 1 Feedforward-path inverter (i.e. 2D + 1F) can achieve a better phase noise than the common 4D + 1F topology at the same frequency and power budget. It is also shown that the bimodal oscillation problem of the 2D + 1F topology can be eliminated by inserting an auxiliary FC path. Prototyped in 65-nm CMOS, the proposed 2D + 1F topology at 3.1 GHz shows a phase noise of -95.1 dBc/Hz at a 1-MHz offset, corresponding to a 159.9 dBc/Hz Figure-of-Merit (FoM) that is 4.2 dB higher than the common 4D + 1F topology.