A magnetic tunnel junction (MTJ) stack incorporating an MgO wedge was deposited over a 200mm wafer and nanofabricated into circular nanopillars with a diameter of 200 nm. Due to the variable MgO thickness, we could obtain MTJ nanopillars with resistance × area (RA) ranging from below 1 Ωμm2 up to 15 Ωμm2 and tunnel magnetoresistance (TMR) ratios up to ~ 100%. It was observed that the ferromagnetic coupling (HF) displayed by the transfer curves increases for smaller values of RA. This variation is attributed to the orange-peel coupling which is caused by the MgO roughness, with a larger impact for thinner barriers. The RF output of the nanopillars, caused by the spin transfer torque induced magnetic precession of the free layer was measured as function of bias current and external magnetic fields for nanopillars with different RA values. Results concerning typical devices in the thin MgO region (1.3 Ωμm2) and in a thicker MgO region (2.7 Ωμm2) are shown, to illustrate the dependences found. It was observed that higher output power (~300 nW) and smaller linewidth (~90 MHz) could be obtained with the higher RA region. These results suggest that there must be an optimum RA value for the production of nano-oscillator devices, which depends on the trade-offs between the need for large breakdown voltages and strong spin polarization of the bias current (favored for larger RA values) and between the need of endurance under large current densities (favored for smaller RA values). Provided the breakdown voltage of the MgO barrrier can be made large enough, nanopillars based in MTJ stacks with an intermediate RA can provide a solution for the production of large output power spin transfer nano-oscillators.