I think they're all pretty similar. For design here in the US, I've used Enercalc and liked it.

But, it probably makes sense to download trial versions of the other two as well.

Enercalc:
+ relatively inexpensive
+ organized similar to how you'd breakdown a building into piecemeal hand calculations

- I've found a lot of errors in the calculations (Biggest offender is the concrete column module under biaxial bending)
- No full building analysis, meant for simple calculations only

Tedds:
+ Very verbose output that reads like a hand calculation, can see each step
+ organized similar to how you'd breakdown a building into piecemeal hand calculations

- At it's heart Tedds is really a word/office plugin (at least that's what the base install was last time we trialed it)
- No full building analysis, meant for simple calculations only

I don't have experience with Prokon.
In my experience either option gives you good return on investment as long as you have proper expectations on how your going to use them.

My Personal Open Source Structural Applications:
https://github.com/buddyd16/Structural-Engineering

Open Source Structural GitHub Group:
https://github.com/open-struct-engineer

Hi Sarakahmed

I use Strand7 and Mecway, the only other alternative that I would consider is Lusas.

I have briefly messed around with Prokon, it is one of the worst packages I have ever used in my life.

I was actually offered to interview for a position at Prokon (about 4 years ago) which I declined the moment I found out which company it was.

It is flooded with mistakes and issues, the support is utterly poor as most of them do not even understand what the software does under the hood.
My own FEM toolbox which I developed on Matlab/Octave actually gave results which lined up with Mecway, Strand7 and NX yet Prokon's results differed.
When querying this I was basically told that the other software companies were incorrect (keeping in mind that SpaceX uses NX). The same held true when I queried aspects about natural frequency analysis. The software is really poor to say the least.

With that been said, Prokon is very popular in South Africa. I think many people don't have the same sentiment that I have since I generally query many things and have a very good understanding of FEA and how software is made.

Hi,I would highly recommend Cross Section Analysis & Design software

The program can check/design any cross section of any material, including steel, R/C, timber etc.
Stress plots under biaxial bending as well as moment vs curvature and interaction curves are created atuomatically.
Moreover, reinforcement is checked or designed as per AASHTO, UBC, AS 3600, IS 456, ACI 318, BS 8110, CSA A233, EC2, NZS 3101, CP 65.
All material stress-strain curves are supported, including negative branches.

Online video tutorials can be found here: https://youtube.com/playlist?list=PL6VbSYX8mIH9s-7...

sarakahmed;
This question is looking for a structural engineering rumble. The answers are different for different folks. And they're willing to die on the hill they choose.
But we've had Enercalc and TEDDS. We've settled on TEDDS for now. Be sure to look at the licensing options. We have a large structural group (35?), and need to make the software available in different locations. TEDDS worked with us (10 seats available at any one time, something like that) for a relatively reasonable cost.
A one or two man operation might analyze it completely differently.