Some benefit we can experience while indoor flying are related to developing the awareness of air pressure on our body and the ability to fine tune our position accordingly.
For those reasons, a thick flappy Cordura suit will filter most of the feedback offer by the wind, as well as disturbing your balance.
With this in mind we recommend to fly modern tight suit, it might make your life a little bit more difficult at first but it will offer the best return for a long term development of your skills, as well as the enjoyment of flying your body instead flying a suit.
There is many great suit on the market but I choose to fly with the TONFLY FLEX and I loves it. Keep in mind that I'm supported by Tonfly so don't believe everything I say, I truly love this brand and how they push the gear helmet and suit in a great direction. My suit was fitting me perfectly at first try, thanks to a very well design measurement chart and the durability is way beyond every suit I ever had prior to this one, with +200H of indoor flying without any sign of wear or tear.
Such a suit is a high quality product, so it is no surprise it comes with a high price tag. So if you are on the budget, you should look at the Neosport suit. This is a full body Lycra Spandex skin used for warm water diving and snorkeling. Around 30€ this suit proved to be good enough for wind tunnel flying, the main downside being a low durability.