Given the discussion about Wizards dominating high level play, I wanted to invert the question, and look at Wizards/Magic- User at low level.
Like before, I think the play at Low Level is very edition dependent, with a general tren of the Wizard being on the weaker end of the spectrum at low level.
1E). Sucked to be a single class MU. 1 spell only. No Crossbow. 1D4 HP, and steep XP requirements. It was hard to live, frankly to even second level. Even at 12th level a MU being hit by a Magic Missle spell by a 1 Lvl MU would likely die or be near death.
2E) Still pretty rough at low level...general rule changes help, a little. Specialization Caster games begin...and helps a bit at low level. Bards can cast almost exactly on par with a MU, due to lower XP costs. Now you are not even the best arcane caster as the MU.
3E). Still pretty rough..but better Play as a Dwarf, and depending on how much of the kitchen sink of feats and spells that are allowed, and you will live to 2nd level.
The Beguilar, War Mage, The Dread Necromancer are better specialists.
The Druid is just plain better than you are, at any point.
You have a crossbow now. You are still running around in your underwear.
4e) 4E probably has the most hardy, and probably most powerful Wizard. Burning Sphere is great. Fireball Sucks. Visions of Avarice FTW.
Magic the requires Subjective DM and Player attention are gone...Phantasmal Force etc.
How often did you find the Wizard was just An after thought at low levels?