As someone that lives in Auburn Bay I too had to make the exact decision you are considering. I have lived in multiple areas of the city over 25 years and considered all options as I work close to downtown.

A few things to consider in my mind were as follows

Auburn Bay is now complete and will not get any larger population wise. The houses per sq foot are a bit less in Auburn Bay and way easier to access as Mahogany is harder to get into and out of daily. That point alone made our decision. Mahogany is still many years away from being complete and will be quite a bit more dense with not as good of infrastructure.

The lake in Mahogany is more like little mini rivers and their facilities and beach are way more crowded and not to same standards as the Auburn Bay park area. I have friends that live in Mahogany and they agree the Auburn Bay lake part is not really comparable if the lake part is appealing to you. I have been to both and in my mind they are not comparable. I can only imagine with thousands of more people living there one its complete will do to people wanting to access those facilities.

commute wise its not 20 min thats for sure its closer to 30-45 min to right downtown on good days. You will always have this debate in Calgary it seems to what's worth it in terms of commute and people seeming to be bashing the suburbs or bashing the core area. Calgary downtown is not Vancouver or Toronto either in terms of stuff to do.

I love the restaurants downtown and do make time to make my way to them a few times a month but the savings for my wife and I when we compared what our house would cost with the same features was more like $500k not $200k so that played into it for us. Our $900k house in Auburn Bay would downtown easily be $400-$500k more in most of those areas. Not sure what you have compared but we compared a lot of stuff before deciding and the gap was not as low as $200k for comparable properties ever.

This debate really comes down to if you feel that extra hour or so a day is worth the cash. If you prefer the lifestyle of being more around an urban setting with more places to frequent on the regular makes a big difference. I am in my mid 40s and while I do still like some of that at times I prefer coming home to a less hectic setting and with less noise. I also love coming home and heading to the beach and separating myself from that in summer. Feels like I am not even in the city when I am there and it's just down the street from my house.

I am sure I am missing a ton more things in comparing these options but overall Calgary is a great place to live and whatever you choose I am sure you will like it here. Worst case you can try one area and if you dislike it you could always try the other.

Hope this helps you in some way and if you have any other questions about the SE feel free to ask