Answer:

Of those three, for us (my partner and I) Viagra was best as far as best erection, when he has had some minor ED problems. But we found some natural means that work just as well without the side effects.

He is taking L-Arginine and pycnogenol daily, and Icariin sometimes a couple of hours before (horny goat weed has icariin in it) Icariin is a pde5 inhibitor just like viagra, just weaker. I did some research and found studies from the national institute of health library and followed those regimes.

Here’s one study:

Treatment of erectile dysfunction with pycnogenol and L-arginine.
Stanislavov R, Nikolova V.
Source

Seminological Laboratory SBALAG, Maichin Dom, Sofia, Bulgaria. rstanik@abv.bg
Abstract

Penile erection requires the relaxation of the cavernous smooth muscle, which is triggered by nitric oxide (NO). We investigated the possibility of overcoming erectile dysfunction (ED) by increasing the amounts of endogenous NO. For this purpose, we orally administered Pycnogenol, because it is known to increase production of NO by nitric oxide syntase together with L-arginine as substrate for this enzyme. The study included 40 men, aged 25-45 years, without confirmed organic erectile dysfunction. Throughout the 3-month trial period, patients received 3 ampoules Sargenor a day, a drinkable solution of the dipeptide arginyl aspartate (equivalent to 1.7 g L-arginine per day). During the second month, patients were additionally supplemented with 40 mg Pycnogenol two times per day; during the third month, the daily dosage was increased to three 40-mg Pycnogenol tablets. We obtained a sexual function questionnaire and a sexual activity diary from each patient. After 1 month of treatment with L-arginine, a statistically nonsignificant number of 2 patients (5%) experienced a normal erection. Treatment with a combination of L-arginine and Pycnogenol for the following month increased the number of men with restored sexual ability to 80%. Finally, after the third month of treatment, 92.5% of the men experienced a normal erection. We conclude that oral administration of L-arginine in combination with Pycnogenol causes a significant improvement in sexual function in men with ED without any side effects.

http://www.ncbi.nlm.nih.gov/pubmed/12851125

And another one:
4 activities.
Xin ZC, Kim EK, Lin CS, Liu WJ, Tian L, Yuan YM, Fu J.
Source

Department of Urology, the 1st Hospital, Peking University, 8 Xishiku Street, Xicheng District, Beijing 100034, China. xinzc@bjmu.edu.cn
Abstract
AIM:

To clarify the mechanism of the therapeutic action of icariin on erectile dysfunction (ED).
METHODS:

PDE5 was isolated from the human platelet and PDE4 from the rat liver tissue using the FPLC system (Pharmacia, Milton Keynes, UK) and the Mono Q column. The inhibitory effects of icariin on PDE5 and PDE4 activities were investigated by the two-step radioisotope procedure with [(3)H]-cGMP/[(3)H]-cAMP. Papaverine served as the control drug.
RESULTS:

Icariin and papaverine showed dose-dependent inhibitory effects on PDE5 and PDE4 activities. The IC(50) of Icariin and papaverine on PDE5 were 0.432 micromol/L and 0.680 micromol/L, respectively and those on PDE4, 73.50 micromol/L and 3.07 micromol/L, respectively. The potencies of selectivity of icariin and papaverine on PDE5 (PDE4/PDE5 of IC(50)) were 167.67 times and 4.54 times, respectively.
CONCLUSION:

Icariin is a cGMP-specific PDE5 inhibitor that may be developed into an oral effective agent for the treatment of ED.

http://www.ncbi.nlm.nih.gov/pubmed/12646997