Starting first IUI with injections soon

Hi all! My DH and I have been TT #1 for 19 months with no luck. My RE and I think I had a chemical pregnancy last month while on Letrolze. I did 3 cycles of Letrolze with no luck. Back ground on us: I don't ovulate every month like I should, very regular periods just very light. DH has low counts, low motility and low morphology. Went back to the RE today and he wants to put me on injectables and try a couple rounds of IUI. My question for everyone out there is, is Follistim or Gonal-f better? Between pain while getting injection and success rate? My insurance company covers more of Follistim, so I'm hoping that it really doesn't matter.I will do an Ovidrel trigger shot as well. Also, any suggestions on how to make the injections not hurt so bad? (I'm a big baby when it comes to pain and needles.)