In 3.5, the Wizard and other Vancian casters would essentially 'know' vastly more spells than the Sorcerer, but, the number they could actually prepare in a day were much closer to the Sorcerer's spells known, and the need to prep spells repeatedly to cast them repeatedly further cut into that, and Sorcerers could cast more spells/day, spontaneously, so never 'wasted' slots, while a prepped Vancian caster might fill a slot with a spell it turned out he never needed. Even with all that, the Sorcerer was often regarded as inferior relegated to Tier 2.
You're assuming an 'optimal' Sorcerer who puts both his metamagic choices towards casting faster (which burns through slots faster, in a game that assumes 6-8 combats per day in an attempt to get casters to conserve those resources at least a little). A Sorcerer with two very different metamagic choices has more options than one where both are focused on the same goal. Burning Sorcerery points for more spell slots (or vice versa) is also an option you're ignoring.
I'm not sure how much that helps, but it's a consideration.
I guess in part I should clarify a little. I'm more focused on low to mid levels than high levels at the moment. Most games don't get to level 15 or 17 but most do get to 11 or 12 so those are the more important levels in explaining how the sorcerer looks. Also, if you aren't feeling effective or good at low levels then you are more likely to switch characters or multi-class. I like sorcerers, but they suffer from a lack of actual options that many people seem to overlook.
Let's look at 3rd to 5th level. This is where a Sorcerer gets half their metamagic (2 options at level 3) and where they get their first big damage spell (typically fireball but my Storm Sorcerer of course took Lightning Bolt)
Twin and Quicken are both good options, for doing separate things that have similar goals. You could Twin Chromatic orbs, Quicken Fireballs and mop up with Fire bolts, ect.
If you want to build an enchanter, support or illusionist the metamagic is still useful, since it is all about timing and targets and that applies to a wide variety of spells.
Empower isn't very useful at 3rd level, you don't have enough damage dice flying around to give it a big impact, but you could get it at 3rd with the assumption of occasionally using it and then having it when you get your 3rd and 4th level spells later on. You could also wait until 10th level when you will definetly have those spells and save your meatmagic option for something more effective at level 3 and level 4.
This option is useless for any build that does not focus on damage, since empower only effects damage.
Heighten spell is very powerful, giving disadvantage to targets, but by costing 3 points at 3rd level this is your entire pool of points. To use heighten spell twice in one day (let's say using 2nd level spells) costs your entire sorcerery pool, 3 1st level spells to refill the pool and the two 2nd level spells you cast. You will not be using this much if you take it, the cost is simply so high that until level 9 it seems unreasonable.
This leaves Subtle, Distant, Careful and Extend.
Subtle is super situational, requiring either being tied up in a dungeon or a high stakes cloak and dagger campagin to be effective enough to even consider.
Distant is rarely useful, since most spells have an effective range (movement speed plus spell range excluding area of effect radius') of 120 ft or more. That is plenty to hit most targets most of the time. Now it does make touch spells range 30 ft which can be useful in combat, but sorcerers do not get many touch spells. In combat ones make distant useful, out of combat ones, less so. Srill I could see someone picking it for flavor, but that means giving up a different option.
Careful is either useful for dealing less damage to allies due to friendly fire or if you can find any spells that require a save that do not deal damage, making those safe for friendly fire. Not a lot of bang for your buck honestly, since most of the time you consider your allies saves or hp to be able to take the friendly fire hit before you cast it anyways.
Extend could be useful, but like distant it is highly subjective to circumstance, since most spell durations are already long enough to accomplish the goals of the casting, extending them is rarely worth the points.
Also, not ignoring being able to turn points into slots, but for the 3 points it takes to make a 2nd level slot you could quicken and twin, or twin and empower twice, or ect. The cost of creating slots is again so high as to make it a major investment of resources, resources that you also need to make your casting as effective as it is supposed to be. You cannot do both metamagic and slot creation on the same day until you start getting to level 10 or higher, at which point a lot of your style and decisons have already been made.
