Wikipedia reports average girth is around 1 1/2". When you go to the dildos section on the site, click refine on the bar on the left. Pick materials (I'd advise you to stick to silicone. Materials like cyber-skin might feel amazing but they are very porous and prone to tears. Pure silicone cock costs more but can last a lifetime), the type of toy and girths - for example from 1 1/4" to 1 1/2" and 1 1/2" to 1 3/4". You can also pick girths but since part of the dildo serves as a handle, dildos tend to be longer than penises. Then you can pick which ones most appeal to you and add them to a comparison. There you can see all the dimensions, pros and cons from the reviews on one page.

The Tantus O2 and Vixen's VixSkin are made of two types of silicone - harder core and softer outer layer to make them more realistic.

Personally my most realistic toy is the Acute - it's much harder a bit narrower than an average cock and I don't insert it to the base. Yes, I'm that shallow I love my Acute and can't wait to find a dual-density friend for it.

Have fun!