No problem. You aren't the first to think that.
It's really hard to keep up with all the different racing sims. Although, I've gravitated to the PC sims, because I'm most interested in very competitive racing, I've had a lot of fun on console titles too.
Many PC sim fans don't give the console sims much credit and many of the console fans don't realize what many of the PC sims have to offer.
iRacing has quite a few Forza and Gran Turismo fans, but it's hard to go back to racing with 8 people online when you've gotten used to up to 43. Bigger fields aren't necessary to have fun, but running at Daytona or Watkins Glen or Indianapolis with 8 drivers just isn't the same as a full field.
Both have their advantages and disadvantages. Console sims tend (big generalization coming) to focus on ambiance, atmosphere, graphics and fun. PC sims tend to focus on physics and realism. Console sims are fun, PC sims are fun too, but with less fanfare and more focused on physics.
iRacing is probably the most hardcore. It's expensive and very competitive. It's collected more of the best PC sim racers all in one place. I've been in competitive sports all my life, so I want to be tested against the best. Thus, even though iRacing is very expensive it's where I spend most of my time.