Since I generally start with rough lumber and don't own any power planers I have to say I prefer the iron plane to the wood body for rough work of smoothing and flattening boards. The extra mass really helps. Anyway I will use a #5 for flattening, trying, jointing and smoothing as well as shooting end grain. That's a lot of work getting done for the investment and the versatility is all the more justification for buying a good tool.
The number 5 takes a common 2 inch wide iron and even if you only have one plane I would suggest two irons that you can hone a little differently if you are going to do all the above tasks. I have one that I hone a pretty good radius on which I use for flattening board across the grain, trying with the grain and edge jointing. the radius allows a deep cut when removing a lot of stock in the flatting and trying process and helps you get the edge square to the face when jointing. The other iron I sharpen straight across and just relieve the corners. This one I use for smoothing and shooting. The straight edge gives a nice smooth surface and a square end when shooting end grain.
I thought about wasting some electrons on the above techniques but I'm certain that they have been covered multiple times in print and on line. Google, YouTube and the local library (I know, how old fashioned) should be all you need to find a ton on the techniques above.
If I were looking for a #5 plane here's a couple I would consider:
- Stanley Bailey planes of pre-war vintage
- Stanley Bedrock planes
- Sargent VBM planes
- Millers Falls planes
- Lie-Nielsen planes