So the simple answer to your question is no, I don't think my beers are sub-par. I think my beers are commercial-quality. Maybe not all at the level of the best craft beers on the market, but if you came to my house and drank from my kegerator, I would think that you'd find my beer to be something that you wouldn't feel uncomfortable paying for at a typical brewery.
I definitely see a few potential things here:
1) Extract/kits. You can make good beer from extract. But it needs to be fresh extract. In a lot of kits, the extract has been packaged for too long and sits around. I'd also say that if you're making Belgian beer from kits, it is probably using light malt extract. This might be too dark for the delicate base of a Belgian beer. If you can get extra-light extract, or even better to use pilsner malt extract, it will probably help some of this. Order from a reputable online source where you expect they have high stock turnover, so that the freshness is better.
2) Racking. Oxygen is the devil when it comes to beer, and *many* people have had issues with autosiphon. I completely swore off the autosiphon early on. If you're seeing bubbles, you're getting O2 in your beer. That's not good. I use
this method which I posted about recently.
3) Water, as others have pointed out. If you're doing extract, just buy big 5 gal bottles of filtered spring water. You don't need distilled or RO for extract. But even for extract, you need water without chlorine/chloramine, and it sounds like your water might be too high in dissolved minerals for "ideal".
4) Secondary. If you're kegging, don't use secondary. Simply rack directly from your fermenter into your serving keg. If you are worried about the beer clearing, let it sit in your kegerator at serving temp for a week and then pull off the first 1-2 cloudy pints. Secondary is just one additional chance to oxidize your beer. A bottling bucket is yet another additional chance to oxidize your beer. Minimizing transfers (particularly since you say you have trouble with oxygen during racking) will help.
5) Kegging vs bottling: If you need to fill bottles, FILL THEM FROM THE KEG. The nice thing about this is that your bottles will be carbonated and clear compared to bottle conditioning. There are methods to fill from the keg that will minimize oxygen pickup, whether it's a counterpressure bottle filler or a
homemade rig.
That's not even getting into fermentation temperature control, which it sounds like you're only marginal on for typical American ales (although for Belgian styles your temps should be ok).
But the key to remember is that making beer is very much process-driven. At each step of your process you have the chance to reduce quality. Honing each process step to minimize the likelihood of doing something that damages the beer will get you there.
And there's always room for improvement. I was making beer I really enjoyed almost 9 years into the hobby. It was consistently good, and I was doing fairly well in competitions when I actually got off my butt and got around to entering. But at that point I went from tap water to RO water + minerals (I do AG). And I
immediately saw a marked improvement in my beer quality, particularly for pale styles (which is often hard to brew with poor water). They went from good to great. And I recently discovered I wasn't even doing it right. I was mistakenly not adding enough acid to my mash water because I wasn't using my spreadsheet right, and so I just changed that two batches ago and am waiting to see how much improvement that very simple adjustment made.
So keep at it. If you keep trying to improve your process, your beers can ABSOLUTELY reach commercial quality consistently.